Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

A method and apparatus for transmitting broadcast signals are discussed. The method can include generating an input stream having plural input packets, link processing the input packets in the input stream to generate link layer packets, physical processing the link layer packets into the broadcast signals, and transmitting the broadcast signals. The link processing can include generating a payload of a link layer packet by encapsulating either a segment of one input packet or concatenated input packets, generating a header of the link layer packet including a base part, the base part including a first field which indicates whether the payload includes either the segment or the concatenated input packets, and inserting the header in front of the payload.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of co-pending U.S. patent applicationSer. No. 14/906,796 filed on Jan. 21, 2016, which is the National Phaseof PCT International Application No. PCT/KR2015/000367 filed on Jan. 14,2015, which claims the benefit under 35 U.S.C. § 119(e) to U.S.Provisional Application No. 61/927,453, filed on Jan. 14, 2014,61/926,958 filed on Jan. 14, 2014 and 61/935,863 filed on Feb. 5, 2014,all of which are hereby expressly incorporated by reference into thepresent application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, thepresent invention provides a method of transmitting broadcast signals.The method of transmitting broadcast signals includes generating pluralinput streams, wherein each of the plural input streams include pluralinput packets; link layer processing the input packets in the pluralinput streams to generate link layer packets; physical layer processingthe link layer packets in physical layer, to generate the broadcastsignals; and transmitting the generated broadcast signals.

Preferably, the link layer processing includes link layer processing oneof the plural input streams based on transparent mode, wherein the linklayer processing one of the plural input streams based on transparentmode includes: delivering the one of the plural input streams to thephysical layer without encapsulating.

Preferably, the link layer processing includes link layer processing oneof the plural input streams based on normal mode, wherein the link layerprocessing one of the plural input streams based on normal modeincludes: encapsulating the input packets in the one of the plural inputstreams to generate the link layer packets, and delivering the generatedlink layer packets to the physical layer.

Preferably, the link layer processing one of the plural input streamsbased on normal mode further includes: overhead reduction processing theinput packets in the one of the plural input streams beforeencapsulating, by compressing headers of the input packets.

Preferably, the link layer processing one of the plural input streamsbased on normal mode further includes: extracting a first signalinginformation from overhead reduction processed input packets, wherein thefirst signaling information is a signaling information to be transmittedin a dedicated transmission channel; and delivering the extracted firstsignaling information to the physical layer.

Preferably, the link layer processing one of the plural input streamsbased on normal mode further includes: extracting second signalinginformation, wherein the second signaling information is for signalingdata in the input packets; encapsulating the extracted second signalinginformation to generate link layer packets; and delivering the generatedlink layer packets to the physical layer.

Preferably, the link layer packet includes a link layer payloadgenerated by using a segment of one of the input packets, or by usingconcatenated input packets.

Preferably, the physical layer processing includes: physical layerprocessing plural Plops (Physical Layer Pipes) including data of thelink layer packets, to generate the broadcast signals.

Preferably, the physical layer processing includes: physical layerprocessing the first signaling information into the dedicatedtransmission channel, to generate the broadcast signals.

Preferably, the input packets are one of TS (Transport Stream) packet,IP (Internet Protocol) packet or GS (Generic Stream) packet.

In other aspect, the present invention provides an apparatus fortransmitting broadcast signals. The apparatus for transmitting broadcastsignals includes a first module that generates plural input streams,wherein each of the plural input streams include plural input packets; asecond module that link layer processes the input packets in the pluralinput streams to generate link layer packets; a third module thatphysical layer processes the link layer packets, to generate thebroadcast signals; and a fourth module that transmits the generatedbroadcast signals.

Preferably, the second module link layer processes one of the pluralinput streams based on transparent mode, wherein the second moduledelivers the one of the plural input streams to the third module withoutencapsulating.

Preferably, the second module link layer processes one of the pluralinput streams based on normal mode, wherein the second moduleencapsulates the input packets in the one of the plural input streams togenerate the link layer packets, and wherein the second module deliversthe generated link layer packets to the third module.

Preferably, the second module overhead reduction processes the inputpackets in the one of the plural input streams before encapsulating, bycompressing headers of the input packets.

Preferably, the second module extracts a first signaling informationfrom overhead reduction processed input packets, wherein the firstsignaling information is a signaling information to be transmitted in adedicated transmission channel; and wherein the second module deliversthe extracted first signaling information to the third module.

Preferably, the second module extracts second signaling information,wherein the second signaling information is for signaling data in theinput packets; wherein the second module encapsulates the extractedsecond signaling information to generate link layer packets; and whereinthe second module delivers the generated link layer packets to the thirdmodule.

Preferably, the link layer packet includes a link layer payloadgenerated by using a segment of one of the input packets, or by usingconcatenated input packets.

Preferably, the third module physical layer processes plural Plops(Physical Layer Pipes) including data of the link layer packets, togenerate the broadcast signals.

Preferably, the third module physical layer processes the firstsignaling information into the dedicated transmission channel, togenerate the broadcast signals.

Preferably, the input packets are one of TS (Transport Stream) packet,IP (Internet Protocol) packet or GS (Generic Stream) packet.

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 30 is a conceptual diagram illustrating a protocol stack for thenext generation broadcast system based on hybrid according to anembodiment of the present invention.

FIG. 31 is a conceptual diagram illustrating an interface of a linklayer according to an embodiment of the present invention.

FIG. 32 is a conceptual diagram illustrating a packet structure of alink elayer according to an embodiment of the present invention.

FIG. 33 shows packet types dependent upon the packet type element valuesaccording to an embodiment of the present invention.

FIG. 34 is a conceptual diagram illustrating a header structure of alink layer packet when an IP packet is transmitted to the link layeraccording to an embodiment of the present invention.

FIG. 35 is a conceptual diagram illustrating the meaning and headerstructures according to C/S field values.

FIG. 36 is a conceptual diagram illustrating the meaning according tothe count field values.

FIG. 37 is a conceptual diagram illustrating the meaning and segmentlengths according to values of Seg_Len_ID field.

FIG. 38 is a conceptual diagram illustrating an equation forencapsulating a normal packet and an equation for calculating a linklayer packet length.

FIG. 39 is a conceptual diagram illustrating a process for encapsulatinga concatenated packet and an equation for calculating a link layerpacket length.

FIG. 40 is a conceptual diagram illustrating a process for calculatingthe length of a concatenated packet including an IPv4 packet and anequation for calculating an offset value at which a length field of theIP packet is located.

FIG. 41 is a conceptual diagram illustrating a process for calculatingthe length of a concatenated packet including an IPv6 packet and anequation for calculating an offset value at which a length field of theIP packet is located.

FIG. 42 is a conceptual diagram illustrating an encapsulation process ofa segmented packet according to an embodiment of the present invention.

FIG. 43 is a conceptual diagram illustrating a segmentation process ofan IP packet and header information of a link layer packet according toan embodiment of the present invention.

FIG. 44 is a conceptual diagram illustrating a segmentation process ofan IP packet including a cyclic redundancy check (CRC) according to anembodiment of the present invention.

FIG. 45 is a conceptual diagram illustrating a header structure of alink layer packet when MPEG-2 TS (Transport Stream) is input to a linklayer according to an embodiment of the present invention.

FIG. 46 shows the number of MPEG-2 TS packets contained in a payload ofthe link layer packet according to values of a count field.

FIG. 47 is a conceptual diagram illustrating a header of the MPEG-2 TSpacket according to an embodiment of the present invention.

FIG. 48 is a conceptual diagram illustrating a process for allowing atransceiver to change a usage of a transport error indicator fieldaccording to an embodiment of the present invention.

FIG. 49 is a conceptual diagram illustrating an encapsulation process ofthe MPEG-2 TS packet according to an embodiment of the presentinvention.

FIG. 50 is a conceptual diagram illustrating an encapsulation process ofthe MPEG-2 TS packet having the same PID according to an embodiment ofthe present invention.

FIG. 51 is a conceptual diagram illustrating an equation for calculatingthe length of a link layer packet through a Common PID reduction processand a Common PID reduction process.

FIG. 52 is a conceptual diagram illustrating the number of concatenatedMPEG-2 TS packets and the length of a link layer packet according tocount field values when Common PID reduction is used.

FIG. 53 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packet including a null packet according to an embodimentof the present invention.

FIG. 54 is a conceptual diagram illustrating a step for processing anindicator configured to count a removed null packet and an equation forcalculating the length of a link layer packet in the processing step.

FIG. 55 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packet including a null packet according to anotherembodiment of the present invention.

FIG. 56 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packets including the same packet identifiers (PIDs) in astream including a null packet according to an embodiment of the presentinvention.

FIG. 57 is a conceptual diagram illustrating an equation for calculatingthe length of a link layer packet when the MPEG-2 TS packets having thesame PIDs are encapsulated in a stream including a null packet accordingto an embodiment of the present invention.

FIG. 58 is a conceptual diagram illustrating a link layer packetstructure for transmitting signaling information according to anembodiment of the present invention.

FIG. 59 is a conceptual diagram illustrating a link layer packetstructure for transmitting the framed packet according to an embodimentof the present invention.

FIG. 60 shows a syntax of the framed packet according to an embodimentof the present invention.

FIG. 61 is a block diagram illustrating a receiver of the nextgeneration broadcast system according to an embodiment of the presentinvention.

FIG. 62 is a conceptual diagram illustrating a general format of asection table according to an embodiment of the present invention.

FIG. 63 is a conceptual diagram illustrating a link layer packet fortransmitting signaling information according to an embodiment of thepresent invention.

FIG. 64 shows the meaning of values denoted by the signaling type field,and contents of a fixed header and an extended header located behind thesignaling type field.

FIG. 65 shows the number of descriptors contained in payload of the linklayer packet according to a concatenation count field value according toan embodiment of the present invention.

FIG. 66 is a conceptual diagram illustrating a process for encapsulatingthe section table into payload when signaling information input to thepayload of the link layer packet is a section table.

FIG. 67 is a conceptual diagram illustrating a syntax of a networkinformation table (NIT) according to an embodiment of the presentinvention.

FIG. 68 is a conceptual diagram illustrating a syntax of a deliverysystem descriptor contained in a network information table (NIT)according to an embodiment of the present invention.

FIG. 69 is a conceptual diagram illustrating a syntax of a fastinformation table (FTT) according to an embodiment of the presentinvention.

FIG. 70 is a conceptual diagram illustrating a process for encapsulatinga descriptor into payload when signaling information input to payload ofthe link layer packet is a descriptor.

FIG. 71 is a conceptual diagram illustrating a syntax of a fastinformation descriptor according to an embodiment of the presentinvention.

FIG. 72 is a conceptual diagram illustrating a delivery systemdescriptor according to an embodiment of the present invention.

FIG. 73 is a conceptual diagram illustrating a process for encapsulatingone GSE-LLC datum into payload of one link layer packet when signalinginformation input to payload of the link layer packet has a GSE-LLCformat used in DVB-GSE.

FIG. 74 is a conceptual diagram illustrating a process for encapsulatingone GSE-LLC datum into payload of several link layer packets whensignaling information input to payload of the link layer packet has aGSE-LLC format used in a DVB-GSE standard.

FIG. 75 illustrates a header of a link layer packet for Robust HeaderCompression (RoHC) transmission according to the present invention.

FIG. 76 illustrates Embodiment #1 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

FIG. 77 illustrates Embodiment #2 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

FIG. 78 illustrates Embodiment #3 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

FIG. 79 illustrates Embodiment #4 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

FIG. 80 illustrates a header of a link layer packet for RoHCtransmission according to an embodiment of the present invention when anMTU is 1,500.

FIG. 81 illustrates Embodiment #1 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

FIG. 82 illustrates Embodiment #2 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

FIG. 83 illustrates Embodiment #3 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

FIG. 84 illustrates Embodiment #4 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

FIG. 85 illustrates Embodiment #5 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

FIG. 86 illustrates Embodiment #6 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

FIG. 87 illustrates Embodiment #7 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

FIG. 88 illustrates a protocol stack for a hybrid-based next generationbroadcast system according to another embodiment of the presentinvention.

FIG. 89 illustrates an operation in a normal mode corresponding to oneof operation modes of a link layer according to an embodiment of thepresent invention.

FIG. 90 illustrates an operation in a transparent mode corresponding toone of operation modes of a link layer according to an embodiment of thepresent invention.

FIG. 91 illustrates a configuration of a link layer at a transmitteraccording to an embodiment of the present invention (normal mode).

FIG. 92 illustrates a configuration of a link layer at a receiveraccording to an embodiment of the present invention (normal mode).

FIG. 93 illustrates a method of transmitting broadcast signals accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL) profiles(base, handheld and advanced profiles), each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≤2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≤2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≤2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs.

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, e1. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010, and aconstellation mapper 6020.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypuncturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permuted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.C _(ldpc)=[I _(ldpc) P _(ldpc)]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹ ,p₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [Math FIG. 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling K_(ldpc) code Type K_(sig) K_(bch) N_(bch) _(—)_(parity) (=N_(bch)) N_(ldpc) N_(ldpc) _(—) _(parity) rate Q_(ldpc) PLS1342 1020 60 1080 4320 3240 1/4  36 PLS2 <1021 >1020 2100 2160 7200 50403/10 56

The LDPC parity puncturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit interleaved PLS1 data andPLS2 data onto constellations.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver. In-band signaling data carries informationof the next TI group so that they are carried one frame ahead of the DPsto be signaled. The Delay Compensating block delays in-band signalingdata accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

The OFDM generation block illustrated in FIG. 8 corresponds to anembodiment of the OFDM generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9100 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9100 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9200 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9200 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9400.

The output processor 9300 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9300 can acquirenecessary control information from data output from the signalingdecoding module 9400. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9400 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9100, demapping & decodingmodule 9200 and output processor 9300 can execute functions thereofusing the data output from the signaling decoding module 9400.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts:

PLS2-STAT data and PLS2-DYN data. The static and dynamic portion of PLS2data is followed by padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 ⅕ 001 1/10 010 1/20 011 1/40 100 1/80 1011/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current PHY_PROFILE = PHY_PROFILE = CurrentPHY_PROFILE = ‘001’ ‘010’ PHY_PROFILE = ‘000’ (base) (handheld)(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile profile present profile present presentpresent FRU_CONFIGURE = Handheld profile Base profile Base profile Baseprofile 1XX present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld profile Handheld profile X1X profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Content PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used for PLS2that is carried in every frame of the next frame-group. The FEC type issignaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2 NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (PI=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field P_(I) N_(TI) 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver. If time interleaving is not used for a DP, it is set to‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DPNUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE ValueIs TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6 Reserved 10Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bit 15 bitHandheld — 13 bit Advanced 13 bit 15 bit

DPNUM_BLOCK: This 10-bit field indicates the number of FEC blocks in thecurrent TI group for the current DP. The value of DP_NUM_BLOCK rangesfrom 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

(a) shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

(a) shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:D _(DP1) +D _(DP2) ≤D _(DP)  [Math FIG. 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

(a) shows an addressing of OFDM cells for mapping type 1 DPs and (b)shows an addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1-1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2-1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction N_(bch) − Rate N_(ldpc) K_(ldpc)K_(bch) capability K_(bch) 5/15 64800 21600 21408 12 192 6/15 2592025728 7/15 30240 30048 8/15 34560 34368 9/15 38880 38688 10/15  4320043008 11/15  47520 47328 12/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error LDPC correction N_(bch) − Rate N_(ldpc) K_(ldpc)K_(bch) capability K_(bch) 5/15 16200 5400 5232 12 168 6/15 6480 63127/15 7560 7392 8/15 8640 8472 9/15 9720 9552 10/15  10800 10632 11/15 11880 11712 12/15  12960 12792 13/15  14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow Math figure.B _(ldpc)=[I _(ldpc) P _(ldpc)]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹ ,p₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [Math FIG. 3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹  [Math FIG. 4]

2) Accumulate the first information bit—i0, at parity bit addressesspecified in the first row of addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

$\begin{matrix}{{{p_{983} = {p_{983} \oplus i_{0}}}{p_{4837} = {p_{4837} \oplus i_{0}}}p_{6138} = {p_{6138} \oplus i_{0}}}{p_{6921} = {p_{6921} \oplus i_{0}}}{p_{7572} = {p_{7572} \oplus i_{0}}}{p_{8496} = {p_{8496} \oplus i_{0}}}{p_{2815} = {p_{2815} \oplus i_{0}}}{p_{4989} = {p_{4989} \oplus i_{0}}}{p_{6458} = {p_{6458} \oplus i_{0}}}{p_{6974} = {p_{6974} \oplus i_{0}}}{p_{8260} = {p_{8260} \oplus i_{0}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 5} \right\rbrack\end{matrix}$

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following Math figure.{x+(s mod 360)×Q _(ldpc)} mod(N _(ldpc) −K _(ldpc))  [Math FIG. 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:

$\begin{matrix}{{{p_{1007} = {p_{1007} \oplus i_{1}}}{p_{1861} = {p_{1861} \oplus i_{1}}}p_{6162} = {p_{6162} \oplus i_{1}}}{p_{6945} = {p_{6945} \oplus i_{1}}}{p_{7596} = {p_{7596} \oplus i_{1}}}{p_{8520} = {p_{8520} \oplus i_{1}}}{p_{2839} = {p_{2839} \oplus i_{1}}}{p_{5013} = {p_{5013} \oplus i_{1}}}{p_{6482} = {p_{6482} \oplus i_{1}}}{p_{6998} = {p_{6998} \oplus i_{1}}}{p_{8284} = {p_{8284} \oplus i_{1}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 7} \right\rbrack\end{matrix}$

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the Math FIG. 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1p _(i) =p _(i) ⊕p _(i-1) ,i=1,2, . . . ,N _(ldpc) −K _(ldpc)−1  [MathFIG. 8]

where final content of pi, i=0, 1, . . . Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Q_(ldpc) 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Q_(ldpc) 5/15 30 6/15 27 7/15 24 8/15 21 9/15 1810/15  15 11/15  12 12/15  9 13/15  6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

(a) shows Quasi-Cyclic Block (QCB) interleaving and (b) showsinner-group interleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type η_(mod) N_(QCB) _(—) _(IG) QAM-16 4 2 NUC-16 44 NUQ-64 6 3 NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-102410 10

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

(a) shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b)shows a cell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,1, c1,1, cη mod-1,1) of the bit interleaving outputis demultiplexed into (d1,0,m, d1,1,m . . . , d1,η mod-1,m) and (d2,0,m,d2,1,m . . . , d2,η mod-1,m) as shown in (a), which describes thecell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,1, c1,1, c9,1) of the Bit Interleaver output is demultiplexed into(d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m . . . , d2,5,m), asshown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

(a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI), where each TI block corresponds to one usage of time interleavermemory. The TI blocks within the TI group may contain slightly differentnumbers of XFECBLOCKs. If the TI group is divided into multiple TIblocks, it is directly mapped to only one frame. There are three optionsfor time interleaving (except the extra option of skipping the timeinterleaving) as shown in the below table 33.

TABLE 33 Modes Descriptions Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH =‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and ismapped to more than one frame. (b) shows an example, where one TI groupis mapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = N_(TI), while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d_(n, s, 0, 0), d_(n, s, 0, 1), …  , d_(n, s, 0, N_(cells) − 1), d_(n, s, 1, 0), …  , d_(n, s, 1, N_(cells) − 1), …  d_(n, s, N_(xBLOCK_TI)(n, s) − 1, 0), …  d_(n, s, N_(xBLOCK_TI)(n, s) − 1, N_(cells) − 1)),

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows.

$d_{n,s,r,q} = \left\{ {\begin{matrix} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu}{SSD}\mspace{14mu}\ldots\mspace{14mu}{encoding}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu}{MIMO}\mspace{14mu}{encoding}}\end{matrix}.} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver aredefined as

(h_(n, s, 0), h_(n, s, 1), …  , h_(n, s, i), …  , h_(n, s, N_(xBLOCK_TI)(n, s) × N_(cells) − 1)),

where h_(n,s,i) is the ith output cell (for i=0, . . . , N_(xBLOCK) _(_)_(TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(_) _(TI)(n,s)

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

shows a writing operation in the time interleaver and (b) shows areading operation in the time interleaver The first XFECBLOCK is writtencolumn-wise into the first column of the TI memory, and the secondXFECBLOCK is written into the next column, and so on as shown in (a).Then, in the interleaving array, cells are read out diagonal-wise.During diagonal-wise reading from the first row (rightwards along therow beginning with the left-most column) to the last row, N_(r) cellsare read out as shown in (b). In detail, assuming z_(n,s,i)(i=0, . . . ,N_(r)N_(c)) as the TI memory cell position to be read sequentially, thereading process in such an interleaving array is performed bycalculating the row index R_(n,s,i) the column index C_(n,s,i), and theassociated twisting parameter T_(n,s,i) as follows expression.

$\begin{matrix}{{{GENERATE}\left( {R_{n,s,j},C_{n,s,j}} \right)} = \left\{ {{R_{n,s,i} = {{mod}\left( {i,N_{r}} \right)}},{T_{n,s,i} = {{mod}\left( {{S_{shift} \times R_{n,s,i}},N_{c}} \right)}},{C_{n,s,i} = {{mod}\left( {{T_{n,s,i} + \left\lfloor \frac{i}{N_{r}} \right\rfloor},N_{c}} \right)}}} \right\}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 9} \right\rbrack\end{matrix}$

where S_(shift) is a common shift value for the diagonal-wise readingprocess regardless of N_(xBLOCk) _(_) _(TI)(n,s), and it is determinedby N_(xBLOCk) _(_) _(TI) _(_) _(MAX) given in the PLS2-STAT as followsexpression.

$\begin{matrix}{{for}\left\{ {{\begin{matrix}{\begin{matrix}{N_{{{xBLOCK}\_{TI}}{\_{MAX}}}^{\prime} =} \\{N_{{{xBLOCK}\_{TI}}{\_{MAX}}} + 1}\end{matrix},} & {{{if}\mspace{14mu} N_{{{xBLOCK}\_{TI}}{\_{MAX}}}{mod}\; 2} = 0} \\{\begin{matrix}{N_{{{xBLOCK}\_{TI}}{\_{MAX}}}^{\prime} =} \\N_{{{xBLOCK}\_{TI}}{\_{MAX}}}^{\prime}\end{matrix},} & {{{{if}\mspace{14mu} N_{{{xBLOCK}\_{TI}}{\_{MAX}}}{mod}\; 2} = 1},}\end{matrix}\mspace{20mu} S_{shift}} = \frac{N_{{{xBLOCK}\_{TI}}{\_{MAX}}} - 1}{2}} \right.} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 10} \right\rbrack\end{matrix}$

As a result, the cell positions to be read are calculated by acoordinate as z_(n,s,i)=N_(r)C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

More specifically, FIG. 27 illustrates the interleaving array in the TImemory for each TI group, including virtual XFECBLOCKs when N_(xBLOCK)_(_) _(TI)(0,0)=3, N_(xBLOCK) _(_) _(TI)(1,0)=6, N_(xBLOCK) _(_)_(TI)(2,0)=5.

The variable number N_(xBLOCK) _(_) _(TI)(n,s)=N_(r) will be less thanor equal to N′_(xBLOCK) _(_) _(TI) _(_) _(MAX). Thus, in order toachieve a single-memory deinterleaving at the receiver side, regardlessof N_(xBLOCK) _(_) _(TI)(n,s), the interleaving array for use in atwisted row-column block interleaver is set to the size ofN_(r)×N_(c)=N_(cells)×N′_(xBLOCK) _(_) _(TI) _(_) _(MAX) by insertingthe virtual XFECBLOCKs into the TI memory and the reading process isaccomplished as follow expression.

[Math FIG. 11] p = 0; for i = 0;i < N_(cells)N_(xBLOCK) _(—) _(TI) _(—)_(MAX)′;i = i + 1 {GENERATE (R_(n,s,i),C_(n,s,i)); V_(i) =N_(r)C_(n,s,j) + R_(n,s,j)  if V_(i) < N_(cells)N_(xBLOCK) _(—)_(TI)(n,s)  {   Z_(n,s,p) = V_(i); p = p + 1;   } }

The number of TI groups is set to 3. The option of time interleaver issignaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’,and DP_TI_LENGTH=T, i.e., NTI=1, IJUMP=1, and PI=1. The number ofXFECBLOCKs, each of which has Ncells=30 cells, per TI group is signaledin the PLS2-DYN data by NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, andNxBLOCK_TI(2,0)=5, respectively. The maximum number of XFECBLOCK issignaled in the PLS2-STAT data by NxBLOCK_Group_MAX, which leads to└N_(xBLOCK) _(_) _(GROUP) _(_) _(MAX)/N_(TI)┘=N_(xBLOCK) _(_) _(TI) _(_)_(MAX)=6.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

More specifically FIG. 28 shows a diagonal-wise reading pattern fromeach interleaving array with parameters of N′_(xBLOCK) _(_) _(TI) _(_)_(MAX)=7 and Sshift=(7−1)/2=3. Note that in the reading process shown aspseudocode above, if V_(i)≥N_(cells)N_(xBLOCK) _(_) _(TI)(n,s), thevalue of Vi is skipped and the next calculated value of Vi is used.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 29 illustrates the interleaved XFECBLOCKs from each interleavingarray with parameters of N′_(xBLOCK) _(_) _(TI) _(_) _(MAX)=7 andSshift=3.

FIG. 30 is a conceptual diagram illustrating a protocol stack for thenext generation broadcast system based on hybrid according to anembodiment of the present invention.

The present invention proposes a data link (encapsulation) part shown inFIG. 30, and proposes a method for transmitting MPEG-2 TS (TransportStream) and/or IP (Internet Protocol) packets received from an upperlayer over a physical layer. In addition, the present invention providesa signaling transmission method needed to operate a physical layer. Inaddition, when transmission of a new packet type is considered in anupper layer in the future, the present invention can implement a methodfor transmitting the new packet transmission information to a physicallayer.

The corresponding protocol layer may also be referred to as a data linklayer, an encapsulation layer, a Layer 2, or the like. For convenienceof description and better understanding of the present invention, theprotocol layer will hereinafter be referred to as a link layer. When theterm “protocol layer” is actually applied to the present invention, itshould be noted that the term “protocol layer” may be replaced with theterm ‘link layer’ or may also be called a new name as necessary.

The broadcast system according to the present invention may correspondto a hybrid broadcast signal implemented by combination of an IP(Internet Protocol) centric broadcast network and a broadband network.

The broadcast system according to the present invention may be designedto be compatible with the legacy MPEG-2 based broadcast system.

The broadcast system according to the present invention may correspondto a hybrid broadcast system based on a combination of the IP centricbroadcast network, a broadband network, and/or a mobile communicationnetwork or cellular network.

Referring to FIG. 30, a physical layer may use a physical protocoladopted by a broadcast system such as the ATSC and/or DVB system.

In an encapsulation layer, an IP datagram may be obtained from specificinformation acquired from a physical layer, or the obtained IP datagrammay be converted into a specific frame (e.g., RS frame, GSE-lite, GSE orsignal frame). In this case, the frame may include an aggregate of IPdatagrams.

A fast access channel (FAC) may include specific information (e.g.,mapping information between a service ID and a frame) used for access toa service and/or contents.

A broadcast system according to the present invention may use a varietyof protocols, for example, Internet Protocol (IP), User DatagramProtocol (UDP), Transmission Control Protocol (TCP), ALC/LCT(Asynchronous Layered Coding/Layered Coding Transport), RCP/RTCP (RateControl Protocol/RTP Control Protocol), HTTP (Hypertext TransferProtocol), FLUTE (File Delivery over Unidirectional Transport), etc. Astack between protocols may refer to the structure of FIG. 30.

In the broadcast system of the present invention, data may betransmitted in the form of ISOBMFF (ISO base media file format). ESG(Electrical Service Guide), NRT (Non Real Time), A/V (Audio/Video)and/or general data may be transmitted in the form of ISOBMFF.

Data transmission caused by the broadcast network may include linearcontent transmission and/or non-linear content transmission.

RTP/RTCP based A/V, and data (closed caption, emergency alert message,etc.) transmission may correspond to linear content transmission.

RTP payload may be encapsulated and transmitted in the form of an RTP/AVstream including a Network Abstraction Layer (NAL) and/or in the form ofan ISO based media file format. RTP payload transmission may correspondto linear content transmission. If the RTP payload is encapsulated andtransmitted in the form of an ISO based media file format, the RTPpayload may include MPEG DASH media segments for A/V or the like.

FLUTE based ESG transmission, non-timed data transmission, and NRTcontent transmission may correspond to non-linear content transmission.The above-mentioned information may be encapsulated and transmitted inthe form of a MIME type file and/or an ISO based media file format. Ifdata is encapsulated and transmitted in the form of an ISO based mediafile format, this data transmission may conceptually include an MPEGDASH media segment for A/V or the like.

Data transmission over the broadband network may be classified intotransmission of contents and transmission of the signaling data.

Content transmission may include transmission of linear content (A/V,data (closed caption, emergency alert messages, etc.), transmission ofnon-linear content (ESG, non-timed data, etc.), and transmission of anMPEG DASH based Media segment (A/V, data).

Transmission of the signaling data may include transmission of dataincluding a signaling table (including MPD of MPEG DASH) transmitted onthe broadcast network.

The broadcast system of the present invention may support not onlysynchronization between linear/non-linear contents having beentransmitted over the broadcast network, but also synchronization betweencontent transmitted over the broadcast network and content transmittedover the broadband network. For example, if one UD content is dividedinto the broadcast network and the broadband network and thensimultaneously transmitted over the broadcast and broadband networks,the receiver may coordinate a timeline dependent upon a transmission(Tx) protocol, may synchronize contents of the broadcast network and thebroadband contents, and may reconstruct the synchronized contents intoone piece of UE content.

An application layer of the broadcast system may implement technicalcharacteristics, for example, interactivity, personalization, secondscreen, ACR (automatic content recognition), etc. The above-mentionedtechnical characteristics are of importance to the North Americanbroadcast standard evolved from ATSC 2.0 to ATSC 3.0. For example, HTML5may be used to implement interactivity.

In a presentation layer of the broadcast system of the presentinvention, HTML and/or HTML may be used to identify the space and timerelationship between components or between bidirectional applications.

The broadcast system according to another embodiment may be implementedby addition or modification of the above-mentioned broadcast system, anda detailed description of the individual constituent elements will bereplaced with that of the above-mentioned broadcast system.

The broadcast system according to another embodiment of the presentinvention may include a system structure compatible with the MPEG-2system. For example, the linear/non-linear contents transmitted in thelegacy MPEG-2 system can be received or operated in the ATSC 3.0 system,and the A/V and data processing may be adaptively coordinated accordingto whether data received by the ATSC 3.0 system is an MPEG-2 TS or IPdatagram.

In an encapsulation layer of the broadcast system according to anotherembodiment of the present invention, information/data obtained from aphysical layer may be converted into the MPEG-2 TS or IP datagram, ormay be converted into a specific frame (e.g., RS frame, GSE-lite, GSE orsignal frame, etc.) using the IP datagram.

The broadcast system according to another embodiment may includesignaling information capable of being adaptively obtained according towhether MPEG-2 TS or IP datagram is used to acquire the service/contentthrough the broadcast network. That is, when obtaining signalinginformation from the broadcast system, the signaling information may beobtained on the basis of MPEG-2 TS, or may be obtained from data basedon a UDP protocol.

The broadcast system of the present invention may supportsynchronization between the linear/non-linear contents based on thebroadcast network encapsulated by MPEG-2 TS and/or IP datagram.Alternatively, the broadcast system can support synchronization betweencontent fragments that are respectively transmitted through thebroadcast network and the broadband network. For example, if one UDcontent is divided into the broadcast network and the broadband networkand then simultaneously transmitted over the broadcast and broadbandnetworks, the receiver may coordinate a timeline dependent upon atransmission (Tx) protocol, may synchronize contents of the broadcastnetwork and the broadband contents, and may reconstruct the synchronizedcontents into one piece of UE content.

FIG. 31 is a conceptual diagram illustrating an interface of a linklayer according to an embodiment of the present invention.

Referring to FIG. 31, the transmitter may consider an exemplary case inwhich IP packets and/or MPEG-2 TS packets mainly used in the digitalbroadcasting are used as input signals. The transmitter may also supporta packet structure of a new protocol capable of being used in the nextgeneration broadcast system. The encapsulated data of the link layer andsignaling information may be transmitted to a physical layer. Thetransmitter may process the transmitted data (including signaling data)according to the protocol of a physical layer supported by the broadcastsystem, such that the transmitter may transmit a signal including thecorresponding data.

On the other hand, the receiver may recover data and signalinginformation received from the physical layer into other data capable ofbeing processed in a higher layer. The receiver may read a header of thepacket, and may determine whether a packet received from the physicallayer indicates signaling information (or signaling data) or recognitiondata (or content data).

The signaling information (i.e., signaling data) received from the linklayer of the transmitter may include first signaling information that isreceived from an upper layer and needs to be transmitted to an upperlayer of the receiver; second signaling information that is generatedfrom the link layer and provides information regarding data processingin the link layer of the receiver; and/or third signaling informationthat is generated from the upper layer or the link layer and istransferred to quickly detect specific data (e.g., service, content,and/or signaling data) in a physical layer.

FIG. 32 is a conceptual diagram illustrating a packet structure of alink elayer according to an embodiment of the present invention.

In accordance with an embodiment of the present invention, the packet ofthe link layer may include a fixed header, an extended header, and/orpayload.

A fixed header is designed to have a fixed size. For example, the fixedheader may be 1 byte long. The extended header can be changed in size.Payload including data received from the higher layer may be locatedbehind the fixed header and the extended header.

The fixed header may include a packet type element and/or an indicatorpart element.

The packet type element may be 3 bits long. The packet type element mayidentify a packet type of a higher layer (i.e., a higher layer of thelink layer). The packet type identified by the packet type element valuewill hereinafter be described in detail.

The indicator part element may include information regarding a payloadconstruction method and/or construction information of the extendedheader. The construction method and/or the construction informationindicated by the indicator part element may be changed according topacket types.

FIG. 33 shows packet types dependent upon the packet type element valuesaccording to an embodiment of the present invention.

Referring to FIG. 33, if the packet type element is set to ‘000’, thismeans that a packet transferred from the higher layer to the link layeris an IPv4 (Internet Protocol version 4) packet.

If the packet type element value is set to ‘001’, this means that apacket transferred from the higher layer to the link layer is an IPv6(Internet Protocol version 6) packet.

If the packet type element value is set to ‘010’, this means that apacket transferred from the higher layer to the link layer is aCompressed IP packet.

If the packet type element value is set to ‘011’, this means that apacket transferred from the higher layer to the link layer is an MPEG-2TS packet.

If the packet type element value is set to ‘101’, this means that apacket transferred from the higher layer to the link layer is aPacketized Stream packet. For example, the Packetized Stream maycorrespond to an MPEG media transport packet.

If the packet type element value is set to ‘110’, this means that apacket transferred from the higher layer to the link layer is a packetfor transmitting signaling information (signaling data).

If the packet type element value is set to ‘111’, this means that apacket transferred from the higher layer to the link layer is a FramedPacket type.

FIG. 34 is a conceptual diagram illustrating a header structure of alink layer packet when an IP packet is transmitted to the link layeraccording to an embodiment of the present invention.

Referring to FIG. 34, if the IP packet is input to the link layer, thepacket type element value may be 000B (3 bits of 000) or 001B (3 bits of001).

Referring to a packet header of the link layer when an IP packet isinput, the indicator part element located next to the packet typeelement may include a C/S (Concatenation/Segmentation) field and/or anadditional bit of 3 bits (hereinafter referred to as an additionalfield).

In case of the packet of the link layer, an additional field of thefixed header and information of the extended header may be decidedaccording to the CS (Concatenation/Segmentation) field of 2 bits locatedbehind the packet type element.

The C/S field indicates the processing type of the input IP packet, andmay include information regarding the extended header length.

In accordance with an embodiment of the present invention, the case inwhich the C/S field is set to 00B (2 bits of 00) may indicate thatpayload of the link layer packet includes a normal packet. The normalpacket may indicate that the input IP packet is used as payload of thelink layer packet without change. In this case, the additional field ofthe fixed header part is not in use, and may be reserved for asubsequent use. In this case, the extended header may not be used.

If the C/S field is set to ‘01B’ (2 bits of ‘01’), this means thatpayload of the link layer packet includes a concatenated packet. Theconcatenated packet includes one or more IP packets. That is, one ormore IP packets may be contained in payload of the link layer packet. Inthis case, the extended header is not used, and the additional fieldlocated subsequent to the C/S field may be used as the count field. Adetailed description of the count field will hereinafter be described indetail.

If the C/S field is set to ‘10B’ (2 bits of ‘10’), this means thatpayload is composed of segmented packets. The segmented packet isobtained by dividing one IP packet into a few segments. Specifically,the segmented packet may include one segment from among the dividedsegments. That is, payload of the link layer packet may include any oneof a plurality of packets contained in the IP packet. The additionalfield located behind the C/S field is used as the segment ID. Thesegment ID may uniquely identify the segment. The segment ID is assignedwhen the IP packet is segmented. In more detail, if segments to berespectively transmitted in the future are integrated, the segment IDcan indicate the presence of a constituent element of the same IPpacket. The segment ID may be 3 bits long, and at the same time cansupport segmentation of the IP packet. For example, the divided segmentsobtained by one IP packet may have the same segment ID. In this case,the extended header may be 1 byte long. In this case, the extendedheader may include the Seg_SN (Segment Sequence Number) field and/or theSeg_Len_ID (Segment Length ID) field.

The Seg_SN field may be 4 bits long, and may indicate a sequence numberof the corresponding segment for use in the IP packet. When the Seg_SNfield IP packet is segmented, the Seg_SN field may be used to confirmthe order or sequence of each segment. Accordingly, although the linklayer packets including a payload segmented from one IP packet may havethe same segment ID (Seg_ID), the link layer packets may have differentSeg_SN field values. The Seg_SN field may be 4 bits long. In this case,one IP packet can be segmented into a maximum of 16 segments. If a userdesires to divide the IP packet into many more segments, the Seg_SNfield is increased in size so that the Seg_SN field may indicate eachorder of the segment and/or the number of segments.

The Seg_Len_ID (Segment Length ID) field may be 4 bits long, and may beused to identify the segment length. The actual segment length accordingto the Seg_Len_ID field value may be identified by a table to bedescribed later. If the length value of an actual segment is signaledinstead of the Seg_Len_ID field, the Seg_Len_ID field of 4 bits may beextended to the segment length field of 12 bits. In this case, theextended header of 2 bytes may be contained in the link layer packet.

If the C/S field value is set to 11B (2 bits of ‘11’), this means anexemplary case in which payload includes the segmented packet as in thecase in which the C/S field value is set to 10B. However, the C/S fieldof 11B may also indicate that the last segment from among severalsegments divided in one IP packet may be contained in a payload. Whensegments are collected to reconstruct one IP packet, the receiver mayidentify the link layer packet configured to transmit the last segmentusing the C/S field value, and the segment contained in the payload ofthe corresponding packet may be recognized as the last segment. Theadditional field located behind the C/S field may be used as the segmentID. In this case, the extended header may be 2 bytes long. The extendedheader may include the Seg_SN (Segment Sequence Number) field and/or theL_Seg_Len (Last Segment Length) field.

The L_Seg_Len field may indicate the actual length of the last segment.If data is segmented to generate the same-sized data segments in theorder from the front part of the IP packet using the Seg_Len_ID field,the last segment may have a different size as compared to anotherprevious segment. Accordingly, the segment length may be directlyindicated using the L_Seg_Len field. The segment length may be changedaccording to the number of allocated bits of the L_Seg_Len field.However, when allocating the number of bits according to the presentinvention, the L_Seg_Len field may indicate that the last segment is1-4095 bytes long.

That is, if one IP packet is divided into a plurality of segments, theIP packet can be divided into a plurality of segments having apredetermined length. However, the length of the last segment may bechanged according to the length of the IP packet. Accordingly, thelength of the last segment needs to be signaled independently. Adetailed description of the field having the same name may be replacedwith the above-mentioned description.

FIG. 35 is a conceptual diagram illustrating the meaning and headerstructures according to C/S field values.

Referring to FIG. 35, if the C/S field is set to ‘00’, this means that anormal packet is contained in the payload of the link layer packet andthe additional field is reserved. On the other hand, the extended headermay not be contained in the link layer packet. In this case, a totallength of the header of the link layer packet may be 1 byte.

If the C/S field is set to ‘01’, a concatenated packet is contained inthe payload of the link layer packet and the additional field may beused as the count field. A detailed description of the count field willbe given later. In the meantime, the extended header may not becontained in the link layer packet. In this case, a total length of theheader of the link layer packet may be 1 byte.

If the C/S field is set to ‘10’, the segmented packet may be containedin the payload of the link layer packet, and the additional field may beused as the segment ID. In the meantime, the extended header may becontained in the link layer packet, and the extended header may includethe Seg_SN field and/or the Seg_Len_ID field. A detailed description ofthe Seg_SN field or the Seg_Len_ID field may be replaced with theabove-mentioned description or a description to be given later. A totallength of the link layer packet may be 2 bytes.

If the C/S field is set to ‘11’, the segmented packet (i.e., packetincluding the last segment) may be contained in the payload of the linklayer packet, and the additional field may be used as the segment ID.Meanwhile, the extended header may be contained in the link layerpacket, and the extended header may include the Seg_SN field and/or theL_Seg_Len field. A detailed description of the Seg_SN field or theL_Seg_Len field may be replaced with the above-mentioned description ora description to be described given. A total length of the link layerpacket may be 3 bytes.

FIG. 36 is a conceptual diagram illustrating the meaning according tothe count field values.

Referring to FIG. 36, the count field may be used in the case in whichthe payload of the link layer packet includes a concatenated packet. Thecount field may indicate how many IP packets are contained in onepayload. The value of the count field may indicate the number ofconcatenated IP packets. However, zero or one concatenation has nomeaning, such that the count field may indicate that the IP packets, thenumber of which is denoted by “count field value+2”, are contained inthe payload. In accordance with one embodiment, 3 bits may be allocatedto the count field, so that this means that a maximum of 9 IP packetshas been contained in the payload of the link layer packet. If there isa need to include many more IP packets in one payload, the length of thecount field may be extended, or 9 or more IP packets of the extendedheader may be additionally signaled.

FIG. 37 is a conceptual diagram illustrating the meaning and segmentlengths according to values of Seg_Len_ID field.

Referring to FIG. 37, the Seg_Len_ID field may be used to indicate thelength of segments other than the last segment from among severalsegments. In order to reduce overhead of the header needed forindicating the segment length, an available segment size may be limitedto 16 segments.

The segment length is decided in response to the packet input sizepredetermined by a code rate of Forward Error Correction (FEC) processedby a physical layer, and the decided segment length may be designated asa length for each value of the Seg_Len_ID field. For example, inassociation with each value assigned to the Seg_Len_ID field, thesegment length may be predetermined. In this case, information regardingthe segment length dependent upon each value of the Seg_Len_ID field isgenerated by the transmitter and transmitted to the receiver, such thatthe receiver may store the received information therein. In themeantime, the segment length established to have each value of theSeg_Len_ID field may be changed. In this case, the transmitter maygenerate new information and transmit the new information to thereceiver, and the receiver may update stored information on the basis ofthe above new information.

In the meantime, if the physical layer processing is performedirrespective of the segment length, the segment length may be calculatedas shown in the equation of FIG. 37.

In Equation of FIG. 37, Len_Unit (Length Unit) may be a basic unit forindicating the segment length, and min_Len may be a minimum value of thesegment length. Len_Unit and min_Len may be set to the same value notonly in the transmitter but also in the receiver. After theabove-mentioned parameters of Equation have been decided once, it ispreferable that the above parameters remain unchanged in terms of systemthroughput. This value may be decided in consideration of the FECprocessing throughput of the physical layer during an initiation processof the system. For example, as shown in FIG. 37, the Len_Unit or min_Lenvalue may indicate the segment length differently represented inresponse to the Seg_Len_ID field value. At this time, the parameter‘Len_Unit’ may be 256, and the parameter ‘min_Len’ may be 512.

FIG. 38 is a conceptual diagram illustrating an equation forencapsulating a normal packet and an equation for calculating a linklayer packet length.

Referring to FIG. 38, if the input IP packet is not concatenated orsegmented within the processing range of the physical layer as describedabove, the IP packet may be encapsulated into a normal packet. Thefollowing contents may be equally applied to IPv4 and IPv6 IP packets.One IP packet may be used as payload of the link layer packet withoutchange, the packet type element value may be set to 000B (IPv4) or 001B(IPv6), and the C/S field value may be set to 00B (Normal Packet). Theremaining three bits of the fixed header may be set to a reserved fieldto be used for another usage in future.

The link layer packet length can be identified as follows. A specificfield indicating the IP packet length may be contained in the header ofthe IP packet. The field indicating the length is always located at thesame position, such that the receiver may confirm the field located at aspecific position spaced apart from an initial part (start part) of thelink layer packet by a predetermined offset, such that the payloadlength of the link layer packet can be recognized.

The receiver can read the length field having the length of 2 bytes at aspecific position spaced apart from the start point of the payload by 2bytes in case of IPv4, and can read the length field having the lengthof 2 bytes at a specific position spaced apart from the start point ofthe payload by 4 bytes in case of IPv6.

Referring to FIG. 38, assuming that the IPv4 length field is set toLIPv4, LIPv4 indicates a total length of IPv4. In this case, if theheader length LH (1 byte) of the link layer packet is added to LIPv4,the length of the entire link layer packet is obtained. In this case, LTmay indicate the length of the link layer packet.

Referring to the equation of FIG. 38, assuming that the IPv6 lengthfield is denoted by LIPv6, LIPv6 indicates only the payload length ofthe IPv6 IP packet. Accordingly, if the header length LH (1 byte) of thelink layer packet is added and the fixed header length (40 bytes) ofIPv6 is additionally added, the length of the link layer packet isobtained. Here, LT may denote the length of the link layer packet.

FIG. 39 is a conceptual diagram illustrating a process for encapsulatinga concatenated packet and an equation for calculating a link layerpacket length.

Referring to FIG. 39, if the input IP packet does not arrive within theprocessing range of the physical layer, some IP packets are concatenatedand encapsulated into one link layer packet. The following descriptioncan also be applied to IP packets of IPv4 and IPv6.

Some IP packets may be used as the payload of the link layer packet, thepacket type element value may be set to 000B (IPv4) or 001B (IPv6), andthe C/S field may be set to 01B (Concatenated Packet). In addition, thecount field of 3 bits indicating how many IP packets are contained inone payload may be concatenated to the C/S field of 01B.

In order to calculate the length of the concatenated packet by thereceiver, a similar way to the normal packet case may be used. Assumingthat the number of concatenated IP packets indicated by the count fieldis denoted by n, the header length of the link layer packet is denotedby LH, and the length of each IP packet is denoted by Lk (where 1≤k≤n),the entire link layer packet length (LT) can be calculated as shown inthe equation.

Since the concatenated packet has the fixed header information only,LH=1 (byte) is achieved, and each Lk (where 1≤k≤n) value can beconfirmed by reading the value of the length field contained in theheader of each IP packet contained in the concatenated packet. Thereceiver may parse the length field of a first IP packet at a specificposition that has a predetermined offset on the basis of a payload startposition after the link layer packet header has ended, and may identifythe length of a first IP packet using this length field. The receivermay parse the length field of a second IP packet at a specific positionthat has a predetermined offset on the basis of a length end point ofthe first IP packet, and may identify the length of the second IP packetusing this length field. The above-mentioned operation is repeated apredetermined number of times corresponding to the number of IP packetscontained in the payload of the link layer packet, so that the payloadlength of the link layer packet can be identified.

FIG. 40 is a conceptual diagram illustrating a process for calculatingthe length of a concatenated packet including an IPv4 packet and anequation for calculating an offset value at which a length field of theIP packet is located.

When the IP packet is input to the transmitter, the transmitter has nodifficulty in reading the length field of the IP packet. However, thereceiver can recognize only the number of IP packets constructing thelink layer packet through the header, such that the position of eachlength field is not well known in the art. However, since the lengthfield is always located at the same position of the header of the IPpacket, the position of the length field is detected using the followingmethod, so that the length of each IP packet contained in the payload ofthe concatenated packet can be calculated and recognized.

Assuming that n IP packets contained in the payload of the concatenatedpacket are respectively denoted by IP1, IP2, . . . IPk, . . . IPn, theposition of the length field corresponding to IPk may be spaced apartfrom a start point of the payload of the concatenated packet by Pkbytes. In this case, Pk (where 1≤k≤n) may be an offset value at whichthe length field of the k-th IP packet is located on the basis of astart point of the payload of the concatenated packet, and the Pk valuecan be calculated as shown in the equation of FIG. 40.

In this case, P1 of the IPv4 packet is 2 bytes. Therefore, the Pk valueis successively updated from P1, and the Lk value corresponding to thePk value is read. If Lk is applied to the equation of FIG. 39, thelength of concatenated packet can be finally calculated.

FIG. 41 is a conceptual diagram illustrating a process for calculatingthe length of a concatenated packet including an IPv6 packet and anequation for calculating an offset value at which a length field of theIP packet is located.

If the IPv6 packets are concatenated and contained in the payload of thelink layer packet, a method for calculating the payload length is asfollows. The length field contained in the IPv6 packet indicatesinformation regarding the payload length of the IPv6 packet, and 40bytes indicating the length of a fixed header of IPv6 are added to thepayload length of the IPv6 packet indicated by the length field, suchthat the length of IPv6 packet can be calculated.

Assuming that n IP packets contained in the payload of the concatenatedpacket are respectively denoted by IP1, IP2, . . . , IPk, . . . , IPn,the position of the length field corresponding to IPk may be spacedapart from the start position of the payload of the concatenated packetby Pk bytes. In this case, Pk (wherein 1≤k≤n) may be an offset value atwhich the length field of the k-th IP packet is located on the basis ofa start point of the payload of the concatenated packet, and may becalculated by the equation shown in FIG. 41. In this case, P1 in case ofIPv6 has 4 bytes. Accordingly, the Pk value is successively updated fromP1, and Lk corresponding to the Pk value is read. If this Lk value isapplied to the equation of FIG. 39, the length of concatenated packetcan be finally calculated.

FIG. 42 is a conceptual diagram illustrating an encapsulation process ofa segmented packet according to an embodiment of the present invention.

The following description can be equally be applied to the IPv4 IPpacket and the IPv6 IP packet. One IP packet is segmented to result in apayload of several link layer packets. The packet type element value maybe set to 000B (IPv4) or 001B (IPv6), and the C/S field value may be 10Bor 11B according to the segment construction.

The C/S field may be set to 11B only in a specific segment correspondingto the last part of the IP packet, and may be set to 10B in theremaining segments other than the above specific segment. The C/S fieldvalue may also indicate information of the extended header of the linklayer packet as described above. That is, if the C/S field is set to10B, the header is 2 bytes long. If the C/S field is set to 11B, theheader is 3 bytes long.

In order to indicate the segmentation state from the same IP packet, theSeg_ID (segment ID) values contained in the headers of the individuallink layer packets must have the same value. In order to allow thereceiver to indicate the order (sequence) information of segments forrecombination of normal IP packets, the sequentially increasing Seg_SNvalues are recorded in the header of each link layer packet.

When the IP packet is segmented, the segment length is decided asdescribed above, and the segmentation process based on the same lengthis carried out. Thereafter, the Seg_Len_ID value appropriate for thecorresponding length information is recorded in the header. In thiscase, the length of the last segment may be changed as compared to theprevious segment, so that the length information may be directlydesignated using the L_Seg_Len field.

The length information designated by the Seg_Len_ID field and theL_Seg_Len field may indicate only payload information of the segment(i.e., link layer packet), such that the receiver may identify thelength information of the entire link layer packet by adding the headerlength of the link layer packet to the payload length of the link layerpacket using the C/S field.

FIG. 43 is a conceptual diagram illustrating a segmentation process ofan IP packet and header information of a link layer packet according toan embodiment of the present invention.

When the IP packet is segmented and encapsulated into the link layerpacket, the field values allocated to the header of respective linklayer packets are shown in FIG. 14.

For example, if the IP packet having the length of 5500 bytes in the IPlayer is input to the link layer, this IP packet is divided into 5segments (S1, S2, S3, S4, S5), and headers (H1, H2, H3, H4, H5) areadded to the 5 segments, so that the added results are encapsulated intothe individual link layer packets.

Assuming that the case of using the IPv4 packet is used, the packet typeelement value may be set to 000B. The C/S field value is set to 10B inthe range of H1˜H4, and the C/S field value of H5 is set to 11B. All thesegment IDs (Seg_IDs) indicating the same IP packet structure may be setto 000B, and the Seg_SN field is sequentially denoted by 0000B˜0100B inthe range of H1˜H5.

The resultant value obtained when 5500 bytes is divided by 5 is 1100bytes. Assuming that the segment is composed of the length of 1024 byteslocated closest to the 1100 bytes, the length of the last segment S5 isdenoted by 1404 bytes (010101111100B). In this case, the Seg_Len_IDfield may be set to 0010B as shown in the above-mentioned example.

FIG. 44 is a conceptual diagram illustrating a segmentation process ofan IP packet including a cyclic redundancy check (CRC) according to anembodiment of the present invention.

When the IP packet is segmented and transmitted to the receiver, thetransmitter may attach the CRC to the rear of the IP packet in such amanner that integrity of combined packets can be confirmed by thereceiver, and finally the segmentation process may be carried out.Generally, since CRS is added to the last part of the packet, the CRS iscontained in the last segment after completion of the segmentationprocess.

When the receiver receives data having a length exceeding the length ofthe last segment, the received data may be recognized as CRC.Alternatively, the length including the CRC length may be signaled asthe length of the last segment.

FIG. 45 is a conceptual diagram illustrating a header structure of alink layer packet when MPEG-2 TS (Transport Stream) is input to a linklayer according to an embodiment of the present invention.

The packet type element may identify that the MPEG-2 TS packet is inputto the link layer. For example, the packet type element value may be setto 011B.

If the MPEG-2 TS is input, the header structure of the link layer packetis shown in FIG. 16. If the MPEG-2 TS packet is input to the link layer,the header of the link layer packet may include the packet type element,the count field, the PI (PID Indicator) field, and/or the DI (DeletedNull Packet Indicator) field.

For example, the 2-bit or 3-bit count field, the 1-bit PI (PIDIndicator) field, and the 1-bit DI (Deleted Null Packet Indicator) fieldmay be arranged subsequent to the packet type of the header of the linklayer packet. If the count field has 2 bits, the remaining 1 bit may beused as a reserved field to be used for a subsequent use in future. Thefixed header part may be constructed in various ways as shown in FIGS.16(a) to 16(d) according to locations of the reserved field. Althoughthe present invention will be disclosed on the basis of the header of(a) for convenience of description and better understanding of thepresent invention, the same description may also be applied to othertypes of headers.

If the MPEG-2 TS packet is input to the link layer (packet type=011),the extended header may not be used.

The count field may indicate how many MPEG-2 TS packets are contained inthe payload of the link layer packet. The size of one MPEG-2 TS packetis greatly less than the size of LDPC (Low-density parity-check) inputindicating the FEC scheme having a high-selection possibility in thephysical layer of the next generation broadcast system, andconcatenation of the link layer can be basically considered. That is,one or more MPEG-2 TS packets may be contained in the payload of thelink layer packet. However, the number of concatenated MPEG-2 TS packetsis limited to some numbers, so that this information may be identifiedby 2 bits or 3 bits. Since the length of the MPEG-2 T packet is fixed toa predetermined size (e.g., 188 bytes), the receiver may also estimatethe payload size of the link layer packet using the count field. Anexample of indicating the number of MPEG-2 TS packets according to thecount field will hereinafter be described in detail.

PI (Common PID indicator) field is set to ‘1’ when the MPEG-2 TS packetscontained in the payload of one link layer packet have the same PIDs(Packet Identifiers). On the contrary, if the MPEG-2 TS packetscontained in the payload of one link layer packet have different PIDs,the PI field is set to ‘0’. The PID field may be 1 bit long.

DI (Null Packet Deletion Indicator) field is set to 1 when a null packetcontained in the MPEG-2 TS packet and then transmitted is deleted. Ifthe null packet is not deleted, the DI field is set to ‘0’. The DI fieldmay be 1 bit long. If the DI field is set to 1, the receiver may reusesome fields of the MPEG-2 TS packet so as to support null packetdeletion in the link layer.

FIG. 46 shows the number of MPEG-2 TS packets contained in a payload ofthe link layer packet according to values of a count field.

If the count field is 2 bits long, the concatenated MPEG-2 TS packetsmay be present in four cases. The payload size of the link layer packetother than synchronous bytes (Sync Bytes) (47H) may also be identifiedby the count field.

The number of MPEG-2 TS packets to be allocated according to the countfield value may be changed according to system designers.

FIG. 47 is a conceptual diagram illustrating a header of the MPEG-2 TSpacket according to an embodiment of the present invention.

Referring to FIG. 47, the header of the MPEG-2 TS packet may include aSync Byte field, a Transport Error Indicator field, a payload unit startindicator field, a transport priority field, a PID field, a transportscrambling control field, an adaptation field control field, and/or acontinuity counter field.

The Sync Byte field may be used for packet synchronization, and may beexcluded in the case of encapsulation at the link layer. A transporterror indicator (EI) located next to the Sync Byte field is not used bythe transmitter, and may be used to inform a higher layer of thepresence of an error incapable of being recovered by the receiver. As aresult, the Transport Error Indicator field is not used by thetransmitter.

The Transport Error Indicator field is established in a demodulationprocess on the condition that it is impossible to correct errors of thestream. In more detail, the Transport Error Indicator field may indicatethe presence of errors incapable of being corrected in the packet.

The payload unit start indicator field may identify whether PES(Packetized elementary stream) or PSI (Program-specific information) isstarted.

The transport priority field may indicate whether the correspondingpacket has a higher priority than other packets having the same PID.

The PID field may identify each packet.

The transport scrambling control field may indicate whether or not ascramble is used, and/or may indicate whether a scramble is used usingan odd or even key.

The adaptation field control field may indicate the presence or absenceof the adaptation field.

The continuity counter field may indicate an order number (or sequencenumber (of the payload packet.

FIG. 48 is a conceptual diagram illustrating a process for allowing atransceiver to change a usage of a transport error indicator fieldaccording to an embodiment of the present invention.

If the DI field is set to 1, the Transport Error Indicator field may beused as a Deletion Point Indicator (DPI) field in the link layer of thetransmitter as shown in FIG. 19. The Deletion Point Indicator (DPI)field may be recovered to the Transport Error Indicator field aftercompletion of the null packet-related processing in the link layer ofthe receiver. That is, the DI field may indicate whether the null packetis deleted, and at the same time may indicate whether the usage of theTransport Error Indicator field of the MPEG-2 TS header is changed.

FIG. 49 is a conceptual diagram illustrating an encapsulation process ofthe MPEG-2 TS packet according to an embodiment of the presentinvention.

Basically, the MPEG-2 TS packet concatenation is being considered, sothat a plurality of MPEG-2 TS packets may be contained in the payload ofone link layer packet, and the number of MPEG-2 TS packets may bedecided as described above. Assuming that the number of MPEG-2 TSpackets contained in payload of one link layer packet is denoted by N,respective MPEG-2 TS packets may be denoted by Mk (wherein 1≤k≤n).

The MPEG-2 TS packet may include a fixed header of 4 bytes and a payloadof 184 bytes. 1 byte from among the header of 4 bytes is used as theSync Byte, and is always assigned the same value (47H). Accordingly, oneMPEG-2 TS packet ‘Mk’ may include the sync part (S) of 1 byte, a fixedheader part (Hk) of 3 bytes other than the sync byte, and/or the payloadpart (Pk) of 184 bytes (wherein 1≤k≤n).

If the adaptation field is used in the header of the MPEG-2 TS packet,the fixed header part is extended even to the front part of theadaptation field, and the remaining adaptation parts are contained inthe payload part.

Assuming that N MPEG-2 TS packets are denoted by [M1, M2, M3, . . . ,Mn], the N MPEG-2 TS packets are arranged in the form of [S, H1, P1, S,H2, P2, . . . , S, Hn, Pn]. The Sync Part is always set to the samevalue, such that the receiver can detect the corresponding positionwithout receiving any signal from the transmitter, and can perform theinsertion action at the detected position. Accordingly, when the payloadof the link layer packet is constructed, the sync part is excluded sothat the packet can be reduced in size. When an aggregate of the MPEG-2TS packets having the above arrangement is constructed as the payload ofthe link layer packet, the sync part is excluded, and the header partand the payload part are separated from each other, so that the MPEG-2TS packets are arranged in the form of [H1, H2, . . . , Hn, P1, P2, . .. , Pn].

If the PI field value is set to zero ‘0’ and the DI field is set to zero‘0’, the payload length of the link layer packet has ‘(n×3)+(n×184)’bytes. Thereafter, if 1 byte indicating the header length of the linklayer packet is added to the resultant bytes, the entire link layerpacket length can be calculated and obtained. That is, the receiver canidentify the length of the link layer packet through the above-mentionedprocess.

FIG. 50 is a conceptual diagram illustrating an encapsulation process ofthe MPEG-2 TS packet having the same PID according to an embodiment ofthe present invention.

If broadcast data is being successively streamed, the MPEG-2 TSscontained in one link layer packet may have the same PDI value. In thiscase, repeated PID values are simultaneously indicated so that the linklayer packet can be reduced in size. In this case, the PI (PIDindicator) field contained in the header of the link layer packet may beused as necessary.

The PI (Common PID Indicator) value of the header of the link layerpacket may be set to ‘1’. As described above, in the case of using NMPEG-2 TS packets [M1, M2, M3, . . . , Mn] within the payload of thelink layer packet, the sync part is excluded, and the header part andthe payload part are separated from each other, so that the MPEG-2 TSpackets may be arranged in the form of [H1, H2, . . . , Hn, P1, P2, . .. , Pn]. In this case, the header parts [H1, H2, . . . , Hn] of theMPEG-2 TS may have the same PID. Although the PID value is indicated andtransmitted only once, the receiver can recover the corresponding datato an original header. Assuming that a common PID is referred to as aCommon PID (CPID) and the header obtained when the PID is excluded fromthe MPEG-2 TS packet header (Hk) is denoted by H′k (where 1≤k≤n), theheader parts [H1, H2, . . . , Hn] of the MPEG-2 TS constructing thepayload of the link layer packet may be reconstructed in the form of[CPID, H′1, H′2, . . . H′n]. This process may be referred to as CommonPID reduction.

FIG. 51 is a conceptual diagram illustrating an equation for calculatingthe length of a link layer packet through a Common PID reduction processand a Common PID reduction process.

Referring to FIG. 51, the header part of the MPEG-2 TS packet mayinclude a PID of 13 bits. If the MPEG-2 TS packets configured toconstruct the payload of the link layer packet have the same PID values,PID is repeated a predetermined number of times corresponding to thenumber of concatenated packets. Accordingly, the PID part is excludedfrom the header parts [H1, H2, . . . , Hn] of the original MPEG-2 TSpacket, so that the MPEG-2 TS packets are reconstructed in the form of[H′1, H′2, . . . H′n], the common PID value is set to the CPID value,and the CIPD may be located at the front of the reconstructed headerpart.

The PID value has the length of 13 bits, and the stuffing bit may beadded in a manner that the entire packet is configured in the form of abyte unit. The stuffing bits may be located at the front or rear part ofthe CPID. The stuffing bits may be properly arranged according to thestructure of concatenated protocol layer or the system implementation.

In the case of encapsulating the MPEG-2 TS packets having the same PID,the PID is excluded from the header part of the MPEG-2 TS packets andthen encapsulated, and the payload length of the link layer packet canbe calculated as described above.

As shown in FIG. 51, the header of the MPEG-2 TS packet other than theSync Byte is 3 bytes long. If the PID part of 13 bits is excluded,resulting in the implementation of 11 bits. Accordingly, if N packetsare concatenated to implement (n×11) bits, and if the number ofconcatenated packets is set to a multiple of 8, the (n×11) bits have thelength of a byte unit. The stuffing bits having the length of 3 bits areadded to the common PID length of 13 bits, so that the CPID part havingthe length of 2 bytes can be constructed.

Therefore, in the case of using the link layer packet obtained when NMPEG-2 TS packets having the same PID are encapsulated, assuming thatthe length of the header of the link layer packet is denoted by LH, theCPID part has the length of LCPID, and a total length of the link layerpacket is denoted by LT, the LT value can be calculated as shown in theequation of FIG. 51.

In the embodiment of FIG. 21, LH is 1 byte, and LCPID is 2 bytes.

FIG. 52 is a conceptual diagram illustrating the number of concatenatedMPEG-2 TS packets and the length of a link layer packet according tocount field values when Common PID reduction is used.

If the number of concatenated MPEG-2 TS packets is decided, and if allpackets have the same PID, the above-mentioned common PID reductionprocess can be applied, and the receiver can calculate the length of thelink layer packets according to the above-mentioned equation.

FIG. 53 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packet including a null packet according to an embodimentof the present invention.

In order to transmit the MPEG-2 TS packet at a fixed transfer rate, thenull packet may be contained in the transmission (Tx) stream. The nullpacket is used as overhead in terms of a transmission aspect, and thus,although the transmitter does not the null packet, the receiver canrecover this null packet. When the transmitter deletes the null packetand transmits data and the receiver searches for the number of deletednull packets and the location of deleted null packets so as to performdata recovery, the null packet deletion indicator (DI) field located inthe header of the link layer packet may be used. In this case, the DIvalue of the header of the link layer packet may be set to 1.

The encapsulation action when the null packet is located at an arbitraryposition between input Tx streams may be carried in a manner that npackets other than the null packet are sequentially concatenated. Thecount value indicating how many null packets are successively excludedmay be contained in the payload of the link layer packet, and thereceiver may generate the null packet at an original position on thebasis of this count value so that the original position is filled withthe null packet.

Assuming that N MPEG-2 TS packets other than the null packet are denotedby [M1, M2, M3, . . . , Mn], the null packet may appear at any positionbetween the MPEG-2 TS packets (M1˜Mn). The part at which the null packetis counted a predetermined number of times from among 0˜n times mayappear in a single link layer packet. That is, assuming that theappearance number of times of the above part at which the null packet iscounted within one link layer packet is denoted by ‘p’, the range of pis denoted by 0 to n.

If the count value of each null packet is denoted by Cm, the range of mis denoted by 1≤m≤p, and Cm does not exist in case of p=0. Specificinformation indicating where each Cm is located between the MPEG-2 TSpackets may be denoted using a specific field in which the usage of EI(transport error indicator) is changed to DPI (Deletion Point Indicator)in the header of the MPEG-2 TS packet.

In the present invention, Cm may have the length of 1 byte. If thepacket to be used later has a margin in length, the 1-byte Cm may alsobe extended. Cm of 1 byte may count a maximum of 256 null packets. Theindicator field of the null packets is located at the header of theMPEG-2 TS packet, and the exclusion of a predetermined number of nullpackets corresponding to “(value denoted by Cm)+1” can be calculated.For example, in case of Cm=0, one null packet may be excluded. In caseof Cm=123, 124 null packets are excluded. If the number of contiguousnull packets is higher than 256, the 257-th null packets are processedas normal packets, and the subsequent null packets can be processed assuch null packets according to the above-mentioned method.

As shown in FIG. 24, the null packet is located between the MPEG-2 TSpackets corresponding to Mi and Mi+1. The count value of the MPEG-2 TSpackets is denoted by C1, and the null packet is located between theMPEG-2 TS packets corresponding to Mj and Mj+1. If the count value ofthe MPEG-2 TS packets may be denoted by Cp, the actual transmissionorder may be denoted by [ . . . , Mi, C1, Mi+1, . . . , Mj, Cp, Mj+1, .. . ].

When the header part and the payload part of the MPEG-2 TS packet,instead of the null packet, are separated from each other and rearrangedto construct the payload of the link layer packet, the count value Cm(1≤m≤p) of the null packets is located between the header part and thepayload part of the MPEG-2 TS packet. That is, the payload of the linklayer packets are arranged in the form of [H1, H2, . . . , Hn, C1, . . ., Cp, P1, P2, . . . , Pn], and the receiver confirms the count value onebyte by one byte in the order shown in the DPI field located at Hk, andrecovers as many null packets as the number of confirmed value accordingto the order of original MPEG-2 TS packets.

FIG. 54 is a conceptual diagram illustrating a step for processing anindicator configured to count a removed null packet and an equation forcalculating the length of a link layer packet in the processing step.

The DPI field may be established to indicate deletion of the null packetand the presence of a count value associated with the deleted nullpacket. As shown in FIG. 25, if the DPI field present at Hi from amongthe header of a plurality of MPEG-2 TS packets is set to 1, this meansthat the null packet located between Hi and Hi+1 is excluded andencapsulated, and its associated 1-byte count value is located betweenthe header part and the payload part.

In the above-mentioned process, the length of the link layer packet canbe calculated by the equation shown in FIG. 54. Therefore, in case ofthe link layer packet that has been obtained by encapsulation of nMPEG-2 TS packets through the null packet exclusion process, assumingthat the header length of the link layer packet is denoted by LH, thecount value Cm (1≤m≤p) of the null packets is denoted by LCount, and thetotal length of the link layer packet is denoted by LT, LT can becalculated by the equation of FIG. 54.

FIG. 55 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packet including a null packet according to anotherembodiment of the present invention.

In accordance with another embodiment of the encapsulation methodexcluding the null packets, payload of the link layer packet can beconstructed. In accordance with another embodiment of the presentinvention, when the header part and payload part of the MPEG-2 TSpackets are rearranged to construct the link layer packet payload, thecount value Cm (1≤m≤p) of the null packets can be located at the headerpart and the order or sequence of the null packets may remain unchanged.That is, the count value of the null packets may be contained at aspecific point at which individual MPEG-2 TS headers are ended.Accordingly, when the receiver reads a value of the DPI field containedin each MPEG-2 TS header, the receiver determines completion of thedeletion of null packets, the receiver reads the count value containedat the last part of the corresponding header, and regenerates as manynull packets as the corresponding count value, such that the regeneratednull packets may be contained in the stream.

FIG. 56 is a conceptual diagram illustrating a process for encapsulatingthe MPEG-2 TS packets including the same packet identifiers (PIDs) in astream including a null packet according to an embodiment of the presentinvention.

The encapsulation process of MPEG-2 TS packets including the same PID(packet identifier) in the stream including the null packet may becarried out by combination of a first process for encapsulating the linklayer packets other than the above null packets and a second process forencapsulating the MPEG-2 TS packets having the same ID into the linklayer packet.

Since an additional PID indicating the null packet is allocated, thecase in which the null packet is contained in the actual transmissionstream is not processed by the same PID. However, after completion ofthe exclusion process of the null packets, only the count value relatedto the null packet is contained in the payload of the link layer packet,the remaining N MPEG-2 TS packets have the same PID, such that the NMPEG-2 TS packets can be processed by the above-mentioned method

FIG. 57 is a conceptual diagram illustrating an equation for calculatingthe length of a link layer packet when the MPEG-2 TS packets having thesame PIDs are encapsulated in a stream including a null packet accordingto an embodiment of the present invention.

In the stream including the null packet, when MPEG-2 TS packets havingthe same PID are encapsulated, the length of the link layer packet canbe calculated through FIG. 51 and/or FIG. 54. The above equations can berepresented by an equation of FIG. 28.

FIG. 58 is a conceptual diagram illustrating a link layer packetstructure for transmitting signaling information according to anembodiment of the present invention.

In order to transmit signaling information before the receiver receivesthe IP packet or the MPEG-2 TS packet in the same manner as in theupdate process of IP header compression information or broadcast channelscan information, the present invention provides packet formats capableof transmitting signaling data (i.e., signaling data) to the link layer.

In accordance with the embodiment of the present invention, if thepacket type element contained in the header of the link layer packet isset to 110B, a section table (or a descriptor) for signaling may becontained in the payload of the link layer packet and then transmitted.The signaling section table may include a signaling table/table sectioncontained in conventional DVB-SI (service information), PSI/PSIP, NRT(Non Real Time), ATSC 2.0, and MH (Mobile/Handheld).

FIG. 59 is a conceptual diagram illustrating a link layer packetstructure for transmitting the framed packet according to an embodimentof the present invention.

Besides the IP packet or the MPEG-2 TS packet, the packet used in ageneral network can be transmitted through the link layer packet. Inthis case, the packet type element of the header of the link layerpacket may be set to 111B, and may indicate that the framed packet iscontained in the payload of the link layer packet.

FIG. 60 shows a syntax of the framed packet according to an embodimentof the present invention.

The syntax of framed packet may include ethernet type, length, and/orpacket( )

The ethernet type which is a 16-bit field shall identify the type ofpacket in the packet( ) field according to the IANA registry. Onlyregistered values shall be used.

The length which is a 16-bit field shall be set to the total length inbytes of the packet( ) structure.

The packet( ) which is variable length field shall contain a networkpacket.

FIG. 61 is a block diagram illustrating a receiver of the nextgeneration broadcast system according to an embodiment of the presentinvention.

Referring to FIG. 61, the receiver according to an embodiment of thepresent invention may include a receiver (not shown), a ChannelSynchronizer 32010, a Channel Equalizer 32020, a Channel Decoder 32030,a Signaling Decoder 32040, a Baseband Operation Controller 32050, aService Map DB 32060, a Transport Packet Interface 32070, a BroadbandPacket Interface 32080, a Common Protocol Stack 32090, a ServiceSignaling Channel Processing Buffer & Parser 32100, an A/V Processor32110, a Service Guide Processor 32120, an Application Processor 32130,and/or a Service Guide DB 32140.

The receiver (not shown) may receive broadcast signals.

The channel synchronizer 32010 may synchronize a symbol frequency withtiming in a manner that signals received at baseband can be decoded. Inthis case, the baseband may indicate a Tx/Rx region of the broadcastsignal.

The channel equalizer 32020 may perform channel equalization of thereceived (Rx) signal. The channel equalizer 32020 may compensate forsignal distortion encountered when the Rx signals are distorted bymultipath, Doppler effect, etc.

The Channel Decoder 32030 may recover the received (Rx) signal into ameaningful transport frame. The channel decoder 32030 may performforward error correction (FEC) of data or transport frame contained inthe Rx signal.

The signaling decoder 32040 may extract and decode signaling datacontained in the received (Rx) signal. Here, the signaling data mayinclude signaling data and/or service information (SI) to be describedlater.

The baseband operation controller 32050 may control baseband signalprocessing.

The Service Map DB 32060 may store signaling data and/or serviceinformation. The service Map DB 32060 may store signaling datacontained/transmitted in the broadcast signal and/or signaling datacontained/transmitted in the broadband packet.

The transport packet interface 32070 may extract the transport packetfrom the transmission (Tx) frame or the broadcast signal. The transportpacket interface 32070 may extract the signaling data or the IP datagramfrom the transport packet.

The broadband packet interface 32080 may receive broadcast-relatedpackets through the Internet. The broadband packet interface 32080 mayextract a packet obtained through the Internet, and combine or extractthe signaling data or A/V data from the corresponding packet.

The common protocol stack 32090 may process the received packetaccording to the protocol contained in the protocol stack. For example,the common protocol stack 32090 may perform processing for eachprotocol, such that it can process the received packet.

The service signaling channel processing buffer & parser 32100 mayextract signaling data contained in the received packet. The servicesignaling channel processing buffer & parser 32100 may scan servicesand/or contents from the IP datagram or the like, and may extractsignaling information related to acquisition of the services and/orcontents, and parse the extracted signaling information. The signalingdata may be located at a predetermined position or channel within thereceived packet. This position or channel may be referred to as aservice signaling channel. For example, the service signaling channelmay have a specific IP address, a UDP Port number, a transmissionsession ID, etc. The receiver may recognize data being transmitted asthe specific IP address, the UDP port number, and the transmissionsession, etc. as signaling data.

The A/V Processor 32110 may perform decoding of the received audio andvideo data, and presentation processing thereof.

The service guide processor 32120 may extract announcement informationfrom the Rx signal, may manage the service guide DB 32140, and providethe service guide.

The application processor 32130 may extract application data containedin the received packet and/or application-associated information, andmay process the extracted data or information.

The service guide DB 32140 may store the service guide data therein.

FIG. 62 is a conceptual diagram illustrating a general format of asection table according to an embodiment of the present invention.

Referring to FIG. 62, the section table according to an embodiment mayinclude a table_id field, a section_syntax_indicator field, asection_length field, a version_number field, a current_next_indicatorfield, a section_number field, a last_section_number field, and/or asection data field.

The table_id field may indicate a unique ID value of the correspondingtable.

The section_syntax_indicator field may indicate a format of a tablesection located behind the corresponding field. If the correspondingfield is set to zero (0), the corresponding table section indicates ashort format. If the corresponding field is set to 1, the correspondingtable section has a general long format. The corresponding field valueaccording to an embodiment of the present invention may always be set to1.

The section_length field may indicate the length of the correspondingsection, such that it can indicate the length from the next part of thecorresponding field to the last part of the corresponding section inbytes.

The version_number field may indicate a version of the correspondingtable.

If the current_next_indicator field is set to 1, this means that thecorresponding section table is valid. If the current_next_indicatorfield is set to 0, this means that the next section table to besubsequently transmitted is valid.

The section_number field may indicate the number of sections containedin the corresponding table. If the first section constructing thecorresponding table is decided, the section_number field value mayindicate zero, and may also be sequentially increased.

The last section_number field may indicate the number of the lastsection from among a plurality of sections constructing thecorresponding table.

The section data field may include data contained in the correspondingsection.

The field denoted by “Special Use” may be a field that can bedifferently configured according to individual tables. The number ofbits allocated to “Special Use” may be maintained without change.

FIG. 63 is a conceptual diagram illustrating a link layer packet fortransmitting signaling information according to an embodiment of thepresent invention.

If signaling information is transmitted using the link layer packet, thevalue of the packet type element may be set to ‘110B’.

FIG. 63 shows a header structure of the link layer packet when signalinginformation is transmitted. Referring to FIG. 63, during transmission ofthe signaling information, a signaling type field of 2 bits may belocated behind the packet type element. The signaling type field mayindicate a format of the signaling information to be transmitted. Theremaining 3-bit part of the fixed header subsequent to the signalingtype field and the extended header may be decided.

If the signaling type field according to an embodiment denotes ‘00B’,this means that the signaling type is a section table. In case of thesection table, information regarding section separation and the sectionlength information are contained in the field of the table, such thatthe link layer packet may indicate only the packet type and thesignaling type without additional processing, and then transmit thepacket type and the signaling type. If the signaling type has a sectiontable format, the remaining 3 bits other than the packet type elementand the signaling type field of the fixed header part are not in use,and may be reserved for a subsequent use. If the signaling type has asection table format, the extended header is not used. If there is aneed to indicate the length of the link layer packet, the extendedheader of 1 or 2 bytes may be added and may be used as a length field.

If the signaling type field according to the embodiment denotes ‘01B’,this means that the signaling type has a descriptor format. Generally,the descriptor is used as some parts of the section table. If only thedescriptor needs to be transmitted through simple signaling, thedescriptor may be transmitted as the corresponding signaling type. Thedescriptor may be shorter in length than the section table, so thatseveral descriptors may be contained in one link layer packet and thentransmitted. 3 bits corresponding to the indicator part of the fixedheader according to the embodiment may be used to indicate how manydescriptors are contained in one link layer packet. If the signalingtype is a descriptor format and the extended header is not in use, thelength of the link layer packet can be displayed using the correspondingdescriptor length information contained in the descriptor without usingthe extended header. If it is necessary to separately display the linklayer packet length, the extended header of 1 or 2 bytes is added, andmay be used as the length field.

The signaling type field value (10B) according to an embodiment may bereserved to support other kinds of signaling.

If the signaling type field according to the embodiment indicates thevalue of 11B, this means that the signaling type is GSE-LLC. The GSE-LLCsignaling may be segmented as necessary. Therefore, if the signalingtype is GSE-LLC, the remaining 3 bits other than the packet type elementand the signaling type field of the fixed header part may be used as thesegment ID. If the signaling type is GSE-LLC, the extended header of 2bytes may be added, and may also be composed of Seg_SN (Segment SequenceNumber) of 4 bits and the length field of 12 bits.

GSE-LLC according to an embodiment is an abbreviation of Generic StreamEncapsulation Logical Link Control, and may indicate one of twoaffiliated layers of the data link layer of the OSI model.

FIG. 64 shows the meaning of values denoted by the signaling type field,and contents of a fixed header and an extended header located behind thesignaling type field.

If the signaling type field according to an embodiment indicates ‘00B’,the field subsequent to the signaling type field may not be present.

If the signaling type field according to an embodiment indicates ‘01B’,the Concatenation Count (Count) field may be located behind thesignaling type field. The Concatenation Count (Count) field may bepresent only when the descriptor instead of the section table istransmitted as signaling information. The Concatenation Count (Count)field may indicate how many descriptors are contained in payload of thelink layer packet. A detailed description of the Concatenation Count(Count) will hereinafter be disclosed.

If the signaling type field according to an embodiment indicates ‘11B’,the Seg_ID (Segment ID) field, the Seg_SN (Segment Sequence Number)field, and/or the length field may be located subsequent to thesignaling type field. In case of LLC signaling data capable of beingtransmitted using DVB_GSE, the LLC signaling data may be autonomouslysegmented. When LLC data is segmented, the Seg_ID (Segment ID) field mayindicate an ID for identifying the segmented data. If segments of thetransmitted LLC data are integrated into one, the receiver may recognizethat the segments of individual LLC data pieces are constituent elementsof the same LLC data using the Seg_ID (Segment ID) field. The Seg_ID(Segment ID) field is 3 bits long, and may identify 8 segments (or 8segmentations). If the Seg_SN (Segment Sequence Number) field issegmented, it may also indicate the order of respective segments. Sincethe index of the corresponding data table is contained in the front partof LLC data, individual segments generated when the receiver receivesthe packet must be sequentially aligned at all times. Although the linklayer packets having payload segmented from one LLC data have the sameSeg_ID, the link layer packets may have different segment sequencenumbers (Seg_SN), and may be 4 longs long. One LLC data may be dividedinto a maximum of 16 segments. The length field may indicate the lengthof LLC data corresponding to the payload of the current link layerpacket in bytes. Accordingly, a total length of the link layer packetmay be denoted by “header length (3 bytes)+Value denoted by the lengthfield”.

DVB_GSE is an abbreviation of DVB-Generic Stream Encapsulation, and mayindicate the data link layer protocol defined by DVB.

FIG. 65 shows the number of descriptors contained in payload of the linklayer packet according to a concatenation count field value according toan embodiment of the present invention.

As many descriptors as the number of specific numerals each beingdenoted by “Concatenation Count (Count) field value+1” may constructpayload of a single link layer packet. Accordingly, since the number ofbits allocated to the Concatenation Count (Count) field is 3, a maximumof 8 descriptors may be composed of one link layer packet.

FIG. 66 is a conceptual diagram illustrating a process for encapsulatingthe section table into payload when signaling information input to thepayload of the link layer packet is a section table.

In accordance with one embodiment of the present invention, one sectiontable may be used as the payload of the link layer packet withoutchange. In this case, a value indicated by the packet type element maybe 110B (signaling), and a value indicated by the signaling type fieldmay be 00B (section table). The remaining 3 bits other than the packettype element and the signaling type field of the fixed header may bereserved for subsequent use.

The field contained in the section table according to an embodiment mayinclude a field indicating the length of the corresponding section. Thefield indicating the length of the corresponding section may always belocated at the same position, and the field shifted from the beginningof the payload of the link layer packet by a predetermined offset isconfirmed, so that the payload length can be confirmed. In case of thesection table, the section length (section_length) field of 12 bits maybe present at a specific position corresponding to movement of 12 bitson the basis of the beginning part of payload. The section_length_fieldmay indicate the length from a part subsequent to thesection_length_field to the last part of the section. Therefore, aspecific part not contained in the section length field and the headerlength of the link layer packet are added to a specific value indicatedby the section length field, so that the length of a total link layerpacket can be derived. In this case, the part (3 bytes) not contained inthe section length field may include a length of the table ID field(table_id field) and a length of the section length field(section_length_field) of the section table. The header length of thelink layer packet may be 1 byte long. That is, the total length of thelink layer packet may be identical to “4 bytes+Value denoted by thesection length field”.

If the receiver according to the embodiment receives the link layerpacket including the section table, the receiver may obtain/useinformation regarding the corresponding section table through the tableID field (table_id field) of 8 bits located subsequent to the fixedheader of the link layer packet.

FIG. 67 is a conceptual diagram illustrating a syntax of a networkinformation table (NIT) according to an embodiment of the presentinvention.

In accordance with the embodiment of the present invention, if thesection table for signaling is contained in payload of the link layerpacket and the resultant section able is transmitted, a networkinformation table indicating information related to the currentbroadcast network may be contained as the section table in the payloadof the link layer packet.

The network information table according to the embodiment may include atable_id field, a section_syntax_indicator field, a section_lengthfield, a network_id field, a version_number field, acurrent_next_indicator field, a section_number field, a lastsection_number field, a network_descriptors_length field, a descriptor() field, a transport_stream_loop_length field, a broadcast id field, anoriginal_network_id field, a delivery_system_descriptor_length field,and/or a delivery_system_descriptor( ) field.

From among a plurality of fields contained in the network informationtable according to the embodiment, some fields having the same titles asthe fields described in the drawing showing a general format of theabove-mentioned section table may be replaced with the above-mentioneddescription.

The network_id field may indicate a unique ID of the broadcast networkbeing currently used.

The network_descriptors_length field may indicate the length ofdescriptor indicating the network associated information at the networklevel.

The descriptor( ) may indicate a descriptor showing the networkassociated information at a network level.

The transport_stream_loop_length field may indicate the length of streamassociated information that is transmitted on the broadcast network.

The broadcast id field may indicate a unique ID of a broadcast stationexisting in the broadcast network.

The original_network_id field may indicate a unique ID of the broadcastnetwork having been originally used. If the originally used broadcastnetwork is different from the current broadcast network, NIT may includeinformation regarding the broadcast network that has been originallyused through the original_network_id field.

The delivery_system_descriptor_length field may indicate the length ofthe descriptor indicating detailed information related to the deliverysystem (delivery_system) on the current broadcast network.

The delivery_system_descriptor( ) may indicate a descriptor includingdetailed information associated with the delivery system(delivery_system) on the current broadcast network.

FIG. 68 is a conceptual diagram illustrating a syntax of a deliverysystem descriptor contained in a network information table (NIT)according to an embodiment of the present invention.

Referring to FIG. 68, the delivery system descriptor according to theembodiment may include information of Physical Layer Pipe (PLP)configured to transmit signaling data related to data transferred from aspecific broadcast station on the transmit (Tx) system.

The delivery system descriptor may include a descriptor_tag field, adescriptor_length field, a delivery_system_id field, a base_PLP_idfield, a base_PLP_version field, and/or a delivery_system_parameters( )field.

The descriptor_tag field may indicate an identifier for indicating thatthe corresponding descriptor is a delivery system descriptor.

The descriptor_length field may indicate the length of the correspondingdescriptor.

The delivery_system_id field may indicate a unique delivery system ID ofthe broadcast network.

The base_PLP_id field may indicate a representative PLP (Physical LayerPipe) for decoding components of the broadcast service transmitted froma specific broadcast station identified by troadcast_id′. In this case,PLP may indicate a data pipe of a physical layer, and may include PSI/SIinformation or the like in a broadcast service transmitted from aspecific broadcast station.

The base_PLP_version field may indicate version information according tovariation of data transmitted through PLP identified by ‘base_PLP_id’.For example, if service signaling such as PSI/SI is transferred throughbase_PLP, the base_PLP_version field value may be increased by onewhenever the service signaling is changed.

The delivery_system_parameters( ) field may include parameters forindicating characteristics of the broadcast delivery system. Theparameters may include a bandwidth, a guard interval, a transmissionmode, a center frequency, etc.

FIG. 69 is a conceptual diagram illustrating a syntax of a fastinformation table (FTT) according to an embodiment of the presentinvention.

In accordance with one embodiment, if the section table for signaling iscontained in payload of the link layer packet and is then transmitted, afast information table (FIT) may be contained as a section table in thepayload of the link layer packet. The receiver according to anembodiment may quickly and easily scan and obtain the broadcast servicethrough the fast information table (FIT).

The fast information table (FIT) may include a table_id field, aprivate_indicator field, a section_length field, a table_id_extensionfield, a FIT_data_version field, a current_next_indicator field, asection_number field, a last_section_number field, a num_broadcastfield, a broadcast id field, a delivery_system_id field, a base_PLP_idfield, a base_PLP_version field, a num_service field, a service_idfield, a service_category field, a service_hidden_flag field, anSP_indicator field, a num_component field, a component_id field, and/ora PLP_id field.

From among a plurality of fields contained in the fast information table(FIT) according to the embodiment, some fields having the same titles asthe fields described in the drawing showing a general format of theabove-mentioned section table may be replaced with the above-mentioneddescription.

The table_id field may indicate that the corresponding table includesinformation related to quick scanning of the service and thecorresponding table corresponds to the fast information table (FIT).

The private_indicator field may always be set to 1.

The table_id_extension field may correspond to some parts of thetable_id field, and provide a scope for the remaining fields.

The FIT_data_version field may indicate version information of thesyntax and semantics contained in the fast information table (FIT). Thereceiver according to the embodiment may decide whether signalinginformation contained in the corresponding table is processed using theFIT_data_version field.

The num_broadcast field may indicate the number of broadcast stationsconfigured to transmit a broadcast service or content through afrequency or a transmitted transport frame.

The broadcast_id field may indicate a unique ID of the broadcast stationconfigured to transmit a broadcast service or content through a fieldfrequency or a transmitted transport frame. In case of the broadcaststation configured to transmit MPEG-2 TS based data, the broadcast_idfield may include the same value as in “transport_stream_id” of MPEG-2TS.

The delivery_system_id field may indicate an identifier of the broadcastdelivery system configured to use the same transmit parameter on thebroadcast network.

The base_PLP_id field may indicate an identifier of PLP configured totransmit the broadcast service signaling information transferred from aspecific broadcast station identified by ‘broadcast_id’. The base_PLP_idfield may indicate a representative PLP for decoding components of thebroadcast service transmitted from a specific broadcast stationidentified by troadcast_id′. In this case, PLP may indicate a data pipeof the physical layer, and may include PSI/SI information in thebroadcast service transferred from a specific broadcast station.

The base_PLP_version field may indicate version information according tovariation of data transmitted through PLP identified by ‘base_PLP_id’.For example, if service signaling information such as PSI/SI istransferred through ‘base_PLP’, the base_PLP_version field value may beincreased by one whenever the service signaling information is changed.

The num_service field may indicate the number of broadcast servicestransferred from a broadcast station identified by ‘broadcast_id’ withinthe corresponding frequency or a transport frame.

The service_id field may indicate an ID for identifying the broadcastservice.

The service_category field may indicate a category of the broadcastservice. For example, if the service_category field value is 0x01, thismeans Basic TV. If the service_category field value is 0x02, this meansBasic Radio. If the service_category field value is 0x03, this means RIservice. If the service_category field value is 0x08, this means ServiceGuide. If the service_category field value is 0x09, this means EmergencyAlerting.

The service_hidden_flag field may indicate whether the correspondingbroadcast service is hidden or not. If the corresponding broadcastservice is hidden, the corresponding service may correspond to a testservice or a service being autonomously used, so that the receiveraccording to the embodiment may disregard the above-mentioned hiddenbroadcast service or may allow the hidden broadcast service to be hiddenfrom the service list.

The SP_indicator field may indicate whether service protection isapplied to one or more components of the corresponding broadcastservice.

The num_component field may indicate the number of components containedin the corresponding broadcast service.

The component_id field may indicate an ID for identifying thecorresponding component of the broadcast service.

The PLP_id field may indicate an identifier for identifying PLP throughwhich the corresponding component is transmitted within the broadcastservice.

FIG. 70 is a conceptual diagram illustrating a process for encapsulatinga descriptor into payload when signaling information input to payload ofthe link layer packet is a descriptor.

In accordance with one embodiment, one or more descriptors may becontained in the payload of the link layer packet. In this case, a valueindicated by the packet type element is set to 110B (signaling), and avalue indicated by the signaling type field may be set to 01B(descriptor). In FIG. 70, the remaining 3 bits other than the packettype element and the signaling type field of the fixed header mayindicate a count field that indicates how many descriptors are containedin the payload of a single link layer packet. The payload of the singlelink layer packet may include a maximum of 8 descriptors.

In accordance with one embodiment, all descriptors may include adescriptor_tag field of 1 byte and a descriptor_length field of 1 bytein the beginning part of the descriptor. In accordance with oneembodiment, the length of a concatenated packet can be calculated usingthe descriptor_length field. The descriptor_length field is alwayslocated at the same position within the descriptor, such that a fieldlocated at a specific position shifted from the beginning part of thepayload of the link layer packet by a predetermined offset is confirmedand therefore the payload length can be confirmed. In case of thedescriptor, the descriptor_length field of 8 bits at a specific positionshifted from the beginning part of the payload by 8 bits may be present.The descriptor_length field may indicate the length from a part locatedbehind the corresponding field to the last part of the descriptor.Therefore, “the length (1 byte) of the descriptor_tag field notcontained in the descriptor_length field+the length (1 bytes) of thedescriptor_length field” are added to a specific value denoted by thedescriptor_length field, so that the length of one descriptor can bederived. As many descriptor lengths as the number of descriptorsindicated by the count field are added so that the length of a totallink layer packet can be derived. For example, a second descriptorcontained in the payload of the link layer packet according to anembodiment may start from a specific position shifted from the beginningpart of the payload by the length of a first descriptor, thedescriptor_length field of the second descriptor is located at aspecific position shifted from the beginning part of the seconddescriptor by a predetermined offset, and the descriptor_length field isconfirmed, so that the total length of the second descriptor can bederived. By the above-mentioned processes, the length of each descriptorcontained in the payload of the link layer packet may be calculated, andthe header length of the link layer packet is added to the sum of thelengths of individual descriptors, so that a total length of the linklayer packet can be calculated.

If the receiver receives the link layer packets including one or moredescriptors, the receiver may obtain/use the signaling informationcontained in each descriptor through the 8-bit descriptor_tag fieldvalue contained in each descriptor.

FIG. 71 is a conceptual diagram illustrating a syntax of a fastinformation descriptor according to an embodiment of the presentinvention.

In accordance with the embodiment, if the descriptor for signaling iscontained in the payload of the link layer packet and then transmitted,the fast information descriptor may be contained in the payload of thelink layer packet. The receiver may quickly and easily scan and obtainthe broadcast service through the fast information descriptor.

The fast information descriptor according to an embodiment may include adescriptor_tag field, a descriptor_length field, a num_broadcast field,a broadcast_id field, a delivery_system_id field, a base_PLP_id field, abase_PLP_version field, a num_service field, a service_id field, aservice_category field, a service_hidden_flag field, and/or anSP_indicator field.

From among a plurality of fields contained in the fast informationdescriptor according to the embodiment, some fields having the sametitles as the fields described in the drawing showing a general formatof the above-mentioned section table may be replaced with theabove-mentioned description.

The descriptor_tag field may indicate a fast information descriptorindicating that the corresponding descriptor includes informationrelated to quick service scanning.

The descriptor_length field may indicate the length of the correspondingdescriptor.

FIG. 72 is a conceptual diagram illustrating a delivery systemdescriptor according to an embodiment of the present invention.

In accordance with one embodiment, if the descriptor for signaling iscontained in the payload of the link layer packet and then transmitted,the delivery system descriptor may be contained in the payload of thelink layer packet. The delivery system descriptor may includeinformation regarding PLP (Physical Layer Pipe) configured to transmitsignaling data related to data transferred from a specific broadcaststation on the transmit (Tx) system.

The delivery system descriptor according to the embodiment may include adescriptor_tag field, a descriptor_length field, a delivery_system_idfield, a num_broadcast field, a base_PLP_id field, a base_PLP_versionfield, a delivery_system_parameters_length field, and/or adelivery_system_parameters( ) field.

The descriptor_tag may indicate that the corresponding descriptor is adelivery system descriptor.

The descriptor_length field may indicate the length of the correspondingdescriptor.

The delivery_system_id field may indicate an ID for identifying adelivery system configured to transmit the same transmit (Tx) parameterson the broadcast network.

The num_broadcast field may indicate the number of broadcast stationsconfigured to transmit a broadcast service or content through afrequency or a transmitted transport frame.

The base_PLP_id field may indicate a representative PLP (Physical LayerPipe) for decoding constituent components of the broadcast servicetransferred from a specific broadcast station identified by‘broadcast_id’. In this case, PLP may denote a data pipe of the physicallayer, and may include PSI/SI information in the broadcast servicetransferred from a specific broadcast station.

The base_PLP_version field may indicate version information according tovariation of data transferred through PLP identified by base_PLP_id. Forexample, if service signaling such as PSI/SI is transferred throughbase_PLP, the base_PLP_version field value may be increased by onewhenever the service signaling is changed.

The delivery_system_parameters_length field may indicate the length ofdelivery_system_parameters( ) subsequent to the corresponding field.

The delivery_system_parameters( ) field may include parameters forindicating characteristics of the broadcast delivery system. Theparameters may include a bandwidth, a guard interval, a transmissionmode, a center frequency, etc.

The delivery system descriptor according to the embodiment may becontained in the network information table (NIT) and then transmitted.

If the delivery system descriptor is contained in the networkinformation table (NIT) and then transmitted, a syntax of the deliverysystem descriptor has already been disclosed in the detailed descriptionof the network information table (NIT).

FIG. 73 is a conceptual diagram illustrating a process for encapsulatingone GSE-LLC datum into payload of one link layer packet when signalinginformation input to payload of the link layer packet has a GSE-LLCformat used in DVB-GSE.

LLC data according to one embodiment may be classified into an indexpart and a record part. The record part may also be classified into afew tables. In this case, the table constructing the record part mayhave a GSE table structure, and may also have a general section tablestructure.

In FIG. 73, one LLC datum may be used as payload of a single link layerpacket. In this case, a value indicated by the packet type element maybe 110B (signaling), and a value indicated by the signaling type fieldmay be 11B (GSE-LLC). If GSE-LLC formatted signaling information istransferred, the link layer packet may have an extended header of 2bytes. The extended header of 2 bytes may be composed of the Seg_SN(segment sequence number) of 4 bytes and the length field of 12 bits.The length field may be assigned a specific value indicating a totallength of the link layer packet according to a system structure, or mayalso be assigned a value indicating the payload length of the link layerpacket.

FIG. 74 is a conceptual diagram illustrating a process for encapsulatingone GSE-LLC datum into payload of several link layer packets whensignaling information input to payload of the link layer packet has aGSE-LLC format used in a DVB-GSE standard.

If LLC data is segmented, the Seg_ID fields indicating segmentation fromLLC data may have the same value.

The Seg_SN field may include the order of segments in such a manner thatthe receiver according to the embodiment receives and recombines thesegmented LLC data. If one LLC datum is contained in the payload of thesingle link layer packet, the Seg_SN field may be set to zero (0).

The receiver according to the embodiment may recognize the number ofsegments of LLC data related to the corresponding Seg_ID through the LLCindex part.

FIG. 75 illustrates a header of a link layer packet for Robust HeaderCompression (RoHC) transmission according to the present invention.

In an Internet Protocol (IP)-based broadcast environment, an IP packetmay be compressed into the above-described link layer packet and betransmitted. When streaming is performed in an IP-based broadcastsystem, information about a header of the IP packet may be rarelychanged and maintained. Based on this fact, the header of the IP packetmay be compressed.

An RoHC scheme is mainly used to compress the header of the IP packet(which is also referred to as an IP header). The present inventionproposes a compression (encapsulation) scheme for a case in which anRoHC packet is input to a link layer.

When the RoHC packet is input to the link layer, the above-describedpacket type element may have a value 010B. The value indicates that apacket delivered from the higher layer to the link layer is a compressedIP packet as described above.

When the RoHC packet is input, the header of the link layer packet mayinclude a fixed header and/or an extended header similarly to the otherpackets described above.

The fixed header may include a packet type field and/or a packetconfiguration (PC) field. The fixed header may have a size of 1 byte intotal. Here, the packet type field corresponds to a case of thecompressed IP packet and thus may have a value of 010. The extendedheader may have a size which is fixed or varies according to a givenembodiment.

The PC field of the fixed header may be a field indicating a form inwhich the RoHC header included in a payload of the link layer packet isprocessed. The PC field has a value that may determine information abouta remaining portion of the fixed header and the extended headerfollowing the PC field. In addition, the PC field may contain lengthinformation of the extended header based on the form in which the RoHCheader is processed. The PC field may have a size of 1 bit.

A case in which the PC field has a value 0B will be described.

The case in which the PC field has the value 0B corresponds to a case inwhich the payload of the link layer packet includes one RoHC packet or aconcatenation of two or more RoHC packets. The concatenation indicatesthat several packets having short lengths are connected to each other toform the payload of the link layer packet.

When the PC field has the value 0B, the PC field may be followed by a1-bit common CID indicator (CI) field and a 3-bit count field. In thisway, the extended header may be additionally provided with common CIDinformation and a length part. The length part may be a part indicatinga length of the RoHC packet.

The CI field may be set to 1 when RoHC packets included in a payload ofone link layer packet have the same context ID (CID), and be set to 0otherwise. When the CI field has a value 1, an overhead processingscheme for a common CID may be applied. The CI field may correspond to 1bit.

The count field may indicate the number of RoHC packets included in thepayload of the one link layer packet. When a concatenation of RoHCpackets is included, the number of the RoHC packets may be indicated bythe count field. The count field may correspond to 3 bits. Thus, amaximum of eight RoHC packets may be included in the payload of the onelink layer packet as shown in Table 34 below. When the count field has avalue 000, one RoHC packet rather than the concatenation of RoHC packetsis included in the payload of the link layer packet.

TABLE 34 Count (3 bits) No. of Concatenated RoHC packets 000 1 001 2 0103 011 4 100 5 101 6 110 7 111 8

As described in the foregoing, the length part may be a part indicatinga length of the RoHC packet. The RoHC packet has an RoHC packet headerexcluding length information. Thus, it is impossible to use a lengthfield in the RoHC packet header.

Therefore, the header of the link layer packet may include the lengthpart to enable a receiver to be aware of a length of the RoHC packet.

When a maximum transmission unit (MTU) is not determined, the IP packethas a maximum length of 65,535 bytes. Thus, 2-byte length information isrequired to support up to a maximum length of the RoHC packet. When aconcatenation of several RoHC packets is included, length fieldscorresponding to the number designated in the count field may beadditionally provided. In this case, the length part may include aplurality of length fields. However, when one RoHC packet is included inthe payload, only one length field may be included. The length fieldsmay be arranged in an order of the RoHC packets included in the payloadof the link layer packet. Each of the length fields may have a value inbytes.

A common CID field may be a field for transmission of the common CID.The RoHC packet may include a CID for verification of a relation betweencompressed headers in a header part. The CID may retain the same valuein a stable link state. Therefore, all the RoHC packets included in thepayload of the one link layer packet may include the same CID. In thiscase, to reduce overhead, CIDs may be removed from header parts ofcontiguous RoHC packets included in the payload, and an associated valuemay be displayed in the common CID field and be transmitted to theheader of the link layer packet. The receiver may recombine the CIDs ofthe RoHC packets using the common CID field. When the common CID fieldis present, the above-described CI field has a value of 1.

A case in which the PC field has a value 1B will be described.

The case in which the PC field has the value 1B corresponds to a case inwhich the payload of the link layer packet includes a segmented packetof the RoHC packet. Here, the segmented packet may correspond to aconfiguration in which the RoHC packet, which is long, is divided into aplurality of segments, and one of the segments is included in thepayload of the link layer packet.

When the PC field has the value 1B, the PC field may be followed by a1-bit last segment indicator (LI) field and a 3-bit segment ID field. Inaddition, to additionally provide information about segmentation, asegment sequence number field, a segment length ID field, a last segmentlength field, and the like may be additionally provided to the extendedheader.

The LI field is a field used when the RoHC packet is segmented. The RoHCpacket may be divided into a plurality of segments. When an LI has avalue 1, a segment currently included in the link layer packet may be alast segment corresponding to one of the segments divided from one RoHCpacket. When the LI has a value 0, a segment currently included in thelink layer packet may not be the last segment. The LI field may be usedto determine whether all the segments are received when the receivercollects the segments to recombine one RoHC packet. The LI field maycorrespond to 1 bit.

The segment ID (Seg_ID) field may be a field indicating an ID assignedto the RoHC packet when the RoHC packet is segmented. All segmentsderived from one RoHC packet may have segment IDs corresponding to thesame value. When the receiver combines respective transmitted segmentsinto one entity, it is possible to determine whether the segmentscorrespond to elements of the same RoHC packet using the segment IDs.The segment ID field may correspond to 3 bits. Therefore, it is possibleto simultaneously support segmentations of eight RoHC packets.

The segment sequence number (Seg_SN) field may be a field used to verifyan order of respective segments when the RoHC packet is segmented. Thatis, link layer packets having segments derived from one RoHC packet aspayloads may have the same Seg_ID and have different Seg_SNs. Therefore,the one RoHC packet may be divided into a maximum of 16 segments.

The segment length ID (Seg_Len_ID) field may be used to express a lengthof each of the segments. However, the segment length ID field may beused to express lengths of a plurality of segments except for the lastsegment. The length of the last segment may be indicated by the lastsegment length field to be described below. The segment length ID fieldmay be present when the payload of the link layer packet does notcorrespond to the last segment of the RoHC packet, that is, the LI has avalue 0.

To reduce overhead of the header, a segment may have a length limited to16. An input size of a packet may be determined based on a code rate offorward error correction (FEC) processed in a physical layer. Thesegment length may be determined based on the input size and bedesignated as a Seg_Len_ID. When the physical layer operatesirrespective of the segment length, the segment length may be determinedas below.Segment Length=Seg_Len_ID×Len_Unit+min_Len [bytes]  [Math FIG. 12]

Here, Len_Unit (Length Unit) is a basic unit for expression of thesegment length, and min_Len may refer to a minimum value of the segmentlength. A transmitter and a receiver have the same values of Len_Unitand min_Len. It is efficient for a system operation when the values donot change after being determined. In addition, Len_Unit and min_Len maybe determined based on an FEC processing ability of the physical layerin a system initialization process.

Table 35 summarizes segment lengths expressed based on values ofSeg-Len_ID. A length assigned to Seg-Len_ID corresponds to an exampleand thus the length may be changed according to intent of a designer. Inthis example, a Len_Unit value is 256, and a min_Len value is 512.

TABLE 35 Seg_Len_ID Segment Length (Byte) 0000 512 (=min_Len) 0001  7680010 1024 0011 1280 0100 1536 0101 1792 0110 2048 0111 2304 1000 25601001 2816 1010 3072 1011 3328 1100 3584 1101 3840 1110 4096 1111 4352

The last segment length (L_Seg_Len) field is a field used when a segmentincluded in the payload of the link layer packet is the last segment ofthe RoHC packet. That is, the last segment length field is a field usedwhen the LI field has a value 1. The RoHC packet may be divided equallyfrom the front part using Seg_Len_ID. In this case, the last segment maynot have a size indicated by Seg_Len_ID. Therefore, the last segment mayhave a length directly indicated by the L_Seg_Len field. The L_Seg_Lenfield may indicate 1 to 4,095 bytes. This may be changed depending on anembodiment.

FIG. 76 illustrates Embodiment #1 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

The present embodiment corresponds to a case in which RoHC packets arewithin a processing range of a physical layer and thus one RoHC packetis included in a payload of the link layer packet. In this case, theRoHC packets are concatenated and may not be segmented.

In this case, the one RoHC packet may become the payload of the linklayer packet without change. A packet type may have a value 010B, a PCfield may have a value 0B, and a CI field may have a value 0B. Theabove-described count field may have a value 000B as described in theforegoing since the one RoHC packet forms the (one) payload withoutchange. The count field may be followed by a 2-byte length fieldindicating a length of an RoHC packet. Only one packet is included inthe payload and thus a length part may include only one length field.

In the present embodiment, a link layer header corresponding to 3 bytesin total may be additionally provided. Therefore, when the RoHC packethas a length of L bytes indicated by the length field, the link layerpacket has a length of L+3 bytes in total.

FIG. 77 illustrates Embodiment #2 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

The present embodiment corresponds to a case in which RoHC packets areout of a processing range of a physical layer and thus a plurality ofRoHC packets are concatenated and included in a payload of the linklayer packet.

In this case, a PC field and a CI field have values corresponding to acase in which one RoHC packet is included in the payload. The PC fieldand the CI field are followed by a count field. As described in theforegoing, the count field may have a value in a range of 001B to 111Bdepending on the number of RoHC packets included in the payload.

Thereafter, 2-byte length fields corresponding to the number indicatedby the count field may be positioned. Each of the length fields mayindicate a length of each of the RoHC packets. The length fields may bereferred to as a length part.

Here, when the number indicated by the count field is n, RoHC packetsR1, R2, . . . , and Rn having lengths L1, L2, . . . , and Ln,respectively, may be concatenated in the payload of the link layerpacket.

An extended header may have a length of 2n bytes in total. A totallength LT of the link layer packet may be expressed by the followingEquation.

$\begin{matrix}{L_{T} = {1 + {2n} + {\sum\limits_{k = 1}^{n}\;{L_{k}\mspace{14mu}\lbrack{bytes}\rbrack}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 13} \right\rbrack\end{matrix}$

FIG. 78 illustrates Embodiment #3 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

The present embodiment corresponds to a case in which a plurality ofRoHC packets are connected to each other (concatenated) to form apayload of the link layer packet, and the concatenated RoHC packets havethe same CID.

When the RoHC packets have the same CID, and a CID is indicated andtransmitted once, a receiver may restore the RoHC packets and headers ofthe RoHC packets. Therefore, a CID common to the RoHC packets may beextracted and transmitted once. In this instance, overhead may bereduced.

In this case, the above-described CI field has a value 1, whichindicates that the same CID is processed. The RoHC packets having thesame CID are indicated by [R1, R2, R3, Rn]. The CID common to the RoHCpackets may be referred to as a common CID. A packet corresponding to anRoHC packet excluding a CID from a header is indicated by R′k (k is 1,2, . . . , or n).

The payload of the link layer packet may include R′k (k is 1, 2, . . . ,or n). A common CID field may be additionally provided to a tail of anextended header of the link layer packet. The common CID field may be afield for transmission of the common CID. The common CID field may betransmitted as a portion of the extended header or as a portion of thepayload of the link layer packet. Depending on a system operation, thecommon CID field may be appropriately rearranged at a portion forverification of a position.

The common CID field may have a size varying according to aconfiguration of the RoHC packet.

When the configuration of the RoHC packet corresponds to a small CIDconfiguration, the RoHC packet may have a CID size of 4 bits. Whenrearrangement is performed by extracting a CID from the RoHC packet, theentire add-CID octet may be processed. That is, the common CID field mayhave a length of 1 byte. Alternatively, after extracting a 1-byteadd-CID octet from the RoHC packet, only a 4-bit CID may be assigned tothe common CID field, and the remaining 4-bit CID may be reserved to beused later.

When the configuration of the RoHC packet corresponds to a large CIDconfiguration, the RoHC packet may have a CID size of 1 byte or 2 bytes.The CID size is determined in an RoHC initialization process. Dependingon the CID size, the common CID field may have a length of 1 byte or 2bytes.

In the present embodiment, the payload of the link layer packet may havea length calculated as below. Lengths of n RoHC packets R1, R2, . . . ,and Rn having the same CID may be referred to as L1, L2, . . . , and Ln,respectively. When the header of the link layer packet has a length LH,the common CID field has a length LCID, and the link layer packet has anentire length LT, LH is as below.L _(H)=1+2n+L _(CID) bytes  [Math FIG. 14]

In addition, LT may be calculated as below.

$\begin{matrix}{L_{T} = {L_{H} + {\sum\limits_{k = 1}^{n}\;{\left( {L_{k} - L_{CID}} \right)\mspace{14mu}{bytes}}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 15} \right\rbrack\end{matrix}$

As described in the foregoing, LCID may be determined based on a CIDconfiguration of the RoHC packet. That is, LCID may be 1 byte for thesmall CID configuration, and may be 1 byte or 2 bytes for the large CIDconfiguration.

FIG. 79 illustrates Embodiment #4 of a method of transmitting an RoHCpacket using a link layer packet, according to the present invention.

The present embodiment corresponds to a case in which respective dividedsegments are compressed (encapsulated) into a payload of a link layerpacket when an input RoHC packet is out of a processing range of aphysical layer.

A PC field has a value 1B to report that the payload of the link layerpacket includes a divided RoHC packet. An LI field has a value 1B onlywhen a segment corresponding to a last portion of the RoHC packet isincluded as the payload, and has a value 0B for all the other segments.The LI field value reports information about an extended header of thelink layer packet. That is, an extended header having a length of 1 bytemay be additionally provided when the LI field has a value 0B, and anextended header having a length of 2 bytes may be additionally providedwhen the LI field has a value 1B.

All Seg_IDs have the same value to indicate segments divided from thesame RoHC packet. Successively increasing Seg_SN values may be recordedin a header to indicate order information of segments for normalrecombination of the RoHC packet in a receiver.

When the RoHC packet is divided, segmentation may be performed bydetermining lengths of segments as described above. A value of aSeg_Len_ID matching a length may be recorded in the header. As describedin the foregoing, a length of a last segment may be directly recorded inan L_Seg_Len field having 12 bits.

Length information indicated using the Seg_Len_ID and the L_Seg_Lenfield may indicate only information about a segment, that is, thepayload of the link layer packet. Therefore, length information of theentire link layer packet may be obtained by adding a header length ofthe link layer packet which may be obtained using the LI field.

In a process of recombining the segments of the RoHC packet at areceiving side, integrity of the recombined RoHC packet needs to beverified. To this end, cyclical redundancy check (CRC) may beadditionally provided at a tail of an IP packet in a segmentationprocess. In general, CRC is additionally provided in a last part of theRoHC packet and thus CRC may be included in the last segment after thesegmentation process.

FIG. 80 illustrates a header of a link layer packet for RoHCtransmission according to an embodiment of the present invention when anMTU is 1,500.

In general, an RoHC scheme may be applied during video and audiostreaming. In this instance, an MTU of an IP packet may be set to 1,500bytes, which indicates that an RoHC packet has a length less than 1,500bytes.

As described in the foregoing, a PC field of a fixed header may be afield that indicates a form in which an RoHC packet included in apayload of the link layer packet is processed. Information about aremaining portion of the fixed header and an extended header followingthe PC field may be determined based on a value of the PC field. Inaddition, the PC field may include length information of the extendedheader based on the form in which the RoHC packet is processed. The PCfield may have a size of 1 bit.

A case in which the PC field has a value 0B will be described.

The case in which the PC field has the value 0B corresponds to a case inwhich the payload of the link layer packet includes one RoHC packet orsegmented packets of the RoHC packet. The PC field may be followed by anSI field. The SI field may indicate whether the payload of the linklayer packet includes one RoHC packet or segments of the RoHC packet.The fixed header and the extended header may have fields determinedbased on a value of the SI field.

As described in the foregoing, the SI field may be a field whichindicates whether the payload of the link layer packet includes one RoHCpacket or segments of the RoHC packet. The SI field having a value 0 mayindicate that the payload of the link layer packet includes one RoHCpacket, and the SI field having a value 1 may indicate that the payloadof the link layer packet includes segments of the RoHC packet. The SIfield may correspond to 1 byte.

A Seg_ID field may be a field which indicates an ID assigned to the RoHCpacket when the RoHC packet is segmented. This field is the same as theSeg_ID field described above.

A Seg_SN field may be a field used to verify an order of respectivesegments when the RoHC packet is segmented. This field is the same asthe Seg_SN field described above.

An LI field may be a field which indicates whether a segment included ina current link layer packet is a last segment among segments dividedfrom the RoHC packet when the RoHC packet is segmented. This field isthe same as the LI field.

A Seg_Len_ID field may be used to express lengths of respectivesegments. This field is the same as the Seg_Len_ID field describedabove. However, unlink the case described above, the segments mayrestrictively have 8 lengths rather than 16 lengths. In this case,lengths of the segments expressed based on values of Seg_Len_ID may besummarized as Table 36 below. A length assigned to Seg_Len_ID is merelyan example, and may be changed according to intent of a designer. In thepresent embodiment, a Len_Unit value is 64, and a min_Len value is 256.

TABLE 36 Seg_Len_ID Segment Length (Byte) 0000 256 (=min_Len) 0001 3200010 384 0011 448 100 512 101 576 110 640 111 704

An L_Seg_Len field may be used to express a length of the last segment.This field is the same as the L_Seg_Len field described above. However,unlink the case described above, the L_Seg_Len field may indicate 1 to2,048 bytes. This may be changed according to an embodiment.

A case in which the PC field has a value 1B will be described.

The case in which the PC field has the value 1B corresponds to a case inwhich the payload of the link layer packet includes a concatenation oftwo or more RoHC packets. The PC field may be followed by a 1-bit CIfield and a 3-bit count field. In this way, the extended header may beadditionally provided with common CID information and a length part.

The CI field is a field which indicates whether RoHC packets included ina payload of one link layer packet have the same CID. The CI field is asdescribed above.

The count field may indicate the number of RoHC packets included in thepayload of the one link layer packet. Unlike the count field describedabove, a value 000 is assigned to indicate a concatenation of two RoHCpackets. When the count field has a value 111, a concatenation of nineof more RoHC packets may be indicated. Count field values are summarizedas the following Table 37.

TABLE 37 Count No. of Concatenated RoHC packets (3 bits) (MTU = 1500bytes) 000 2 001 3 010 4 011 5 100 6 101 7 110 8 111 9 or more packets,Extended length field is used

The length part may be a part for indication of a length of the RoHCpacket. The length part may include a plurality of length fields asdescribed above. Each of the length fields may indicate a length of eachRoHC packet.

In the present embodiment, an MTU corresponds to 1,500 bytes and thus 11bits corresponding to a minimum bit for indication of the MTU may beassigned to a length field. Since 11 bits may indicate up to 2,048bytes, a scheme proposed in the present invention may be used even whenthe MTU is extended up to 2,048 bytes as necessary. The length field maydirectly indicate a length, and indicate the length by mapping thelength to a separate value. As described in the foregoing, length fieldscorresponding to the number designated in the count field may beadditionally provided.

An extended length part may be used to indicate a length of a ninth RoHCpacket or an RoHC packet after the ninth RoHC packet when nine of moreRoHC packets are concatenated. That is, the extended length part may beused when the count field has a value 111B. The extended length part mayinclude an 11-bit length field and a 1-bit X field. The two fields maybe alternately positioned.

A common CID field may be a field for transmission of a common CID. Thisfield may be the same as the common CID field described above.

FIG. 81 illustrates Embodiment #1 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

The present embodiment may correspond to a case in which a PC field hasa value 1 and a count field has a value other than 111B when the MTU is1,500.

In this case, a length part may have length fields corresponding to thenumber designated by a count field value as described above. Since onelength field corresponds to 11 bits, a padding bit may be additionallyprovided depending on the number of the length fields. That is, when thenumber designated by the count field is set to k, and a size of the onelength field is set to s (bits), a length LLP of the entire length partmay be calculated as below.

$\begin{matrix}{L_{LP} = {\left\lceil \frac{k \times s}{8} \right\rceil\mspace{14mu}\lbrack{Bytes}\rbrack}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 16} \right\rbrack\end{matrix}$

In addition, a size of the padding bit additionally provided to thelength part may be calculated as below.L _(padding)=(8×L _(LP))−(k×s) [Bits]  [Math FIG. 17]

As described in the foregoing, the length s of the length field may be11 bits, which may be used to summarize the sizes of the length part andthe padding bit as below.

TABLE 38 No. of Concatenated Count RoHC packets Size of Length Part Sizeof Padding (3 bits) (MTU = 1500 bytes) (Bytes) (bits) 000 2 3 2 001 3 57 010 4 6 4 011 5 7 1 100 6 9 6 101 7 10 3 110 8 11 1

FIG. 82 illustrates Embodiment #2 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

The present embodiment may correspond to a case in which a PC field hasa value 1 and a count field has a value 111B when the MTU is 1,500. Inthis case, an extended length part may be additionally provided asdescribed above.

A length part positioned in front of the extended length part includeseight 11-bit length fields and thus may have a length of 11 bytes intotal. Since the count field has the value 111, the extended length partneeds to include at least one length field.

As described in the foregoing, the extended length part may include an11-bit length field and a 1-bit X field. The two fields may bealternately positioned. The length field of the extended length part maybe operated similarly to the length fields of the length part.

The X field may be a field which indicates whether the X field isadditionally followed by a length field. When the X field has a value 0,no length field may be additionally provided. When the X field has avalue 1, the X field may be followed by at least one length field and anX field. Therefore, the extended length part may continuously increaseuntil the X field has the value 0. RoHC packets equal in number to Xfields may be additionally positioned in a payload.

When the number of X fields having the value 1 is set to m and a size ofone length field is set to s (bits) in the extended length part, alength LELP of the extended length part may be calculated as below.

$\begin{matrix}{L_{ELP} = {\left\lceil \frac{\left( {m + 1} \right) \times \left( {s + 1} \right)}{8} \right\rceil\mspace{14mu}\lbrack{Bytes}\rbrack}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 18} \right\rbrack\end{matrix}$

The extended length part may also have a padding bit for processing inbytes. The padding bit additionally provided in the extended length partmay have a size calculated as below.L _(E) _(_) _(padding)=(8×L _(ELP))−((m+1)×(s+1)) [Bits]  [Math FIG. 19]

A padding bit of 4 bits may be additionally provided when the number oflength fields is an odd number, and no padding bit may be additionallyprovided when the number of length fields is an even number.

FIG. 83 illustrates Embodiment #3 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

The present embodiment may correspond to a case in which RoHC packetsare within a processing range of a physical layer and thus one RoHCpacket is included in a payload of the link layer packet.

In this case, the one RoHC packet may be the payload of the link layerpacket without change. A packet type may have a value 010B, a PC fieldmay have a value 0B, and an SI field may have a value 0B. Theabove-described length part may follow the PC and SI fields. Here, thelength part may have one length field. The length field may correspondto 11 bits. 3 bits of a fixed header and 1 byte of an extended headermay be used for the one 11-bit length field.

In this case, a link layer header having 2 bytes in total isadditionally provided. Therefore, when the RoHC packet indicated by thelength field has a length of L bytes, the link layer packet has a totallength of L+2 bytes.

FIG. 84 illustrates Embodiment #4 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500 according to thepresent invention.

The present embodiment may correspond to a case in which respectivedivided segments are compressed (encapsulated) into a payload of thelink layer packet when the MTU is 1,500 and an input RoHC packet is outof a processing range of a physical layer.

An SI field may have a value 1 to indicate segmentation.

As described in the foregoing, Seg_IDs have the same value, and Seg_SNshave successively increasing values. An LI field has a value 1 for alast segment and has a value 0 otherwise. In addition, Seg_Len_ID andL_Seg_Len fields may be used to indicate a length of each segment. Adetailed scheme of indicating a length may be similar to that describedabove.

Length information of the entire link layer packet may be obtained byadding a header length of the link layer packet which may be obtainedusing the LI field. In addition, CRC may be additionally provided toverify integrity in a process of recombining the segments of the RoHCpacket at a receiving side. The CRC may be additionally provided to thelast segment.

FIG. 85 illustrates Embodiment #5 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

The present embodiment may correspond to a case in which RoHC packetsare out of a processing range of a physical layer and thus a pluralityof RoHC packets are concatenated and included in a payload of the linklayer packet when the MTU is 1,500.

The present embodiment may correspond to a case in which eight or lessRoHC packets are concatenated. In this case, an extended length part maynot be needed. A PC field may have a value 1, and a CI field may have avalue 0. A count field may have a value in a range of 000B to 110B asdescribed above.

Here, when a value indicated by the count field is n, RoHC packets R1,R2, . . . , and Rn having lengths L1, L2, . . . , and Ln, respectively,may be concatenated in the payload of the link layer packet. Each lengthfield may have a length of 11 bits. A padding bit may be positioned at atail of the length field as necessary.

A length LT of the entire link layer packet is as below.

$\begin{matrix}{L_{T} = {1 + L_{LP} + {\sum\limits_{k = 1}^{n}\;{L_{k}\mspace{14mu}\lbrack{bytes}\rbrack}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 20} \right\rbrack\end{matrix}$

Here, LLP may denote a length of the entire length part, and LK maydenote a length of each RoHC packet.

FIG. 86 illustrates Embodiment #6 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

The present embodiment may correspond to a case in which RoHC packetsare out of a processing range of a physical layer and thus a pluralityof RoHC packets are concatenated and included in a payload of the linklayer packet when the MTU is 1,500.

However, the present embodiment may correspond to a case in which nineor more RoHC packets are concatenated. In this case, an extended lengthpart may be needed in addition to a length part. As described in theforegoing, a count field may have a value 111.

When the number of X fields, each of which has a value 1, is set to m inthe extended length part, the number n of RoHC packets concatenated inthe payload of the link layer packet is 8+(m+1). In this instance, alength LT of the entire link layer packet is as follows.

$\begin{matrix}{L_{T} = {1 + L_{LP} + L_{ELP} + {\sum\limits_{k = 1}^{n}\;{L_{k}\mspace{14mu}\lbrack{bytes}\rbrack}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 21} \right\rbrack\end{matrix}$

Here, LLP may be a length of the entire length part, and Lk may be alength of each of the RoHC packets. In addition, LELP may be a length ofthe entire extended length part.

FIG. 87 illustrates Embodiment #7 of a method of transmitting an RoHCpacket using a link layer packet when an MTU is 1,500, according to thepresent invention.

The present embodiment may correspond to a case in which a plurality ofRoHC packets are concatenated to form a payload of the link layer packetwhen the MTU is 1,500. However, the present embodiment corresponds to acase in which the concatenated RoHC packets have the same CID.

In this case, the above-described CI field has a value 1, whichindicates that the same CID is processed. The RoHC packets having thesame CID are indicated by [R1, R2, R3, . . . , Rn]. The CID common tothe RoHC packets may be referred to as a common CID. A packetcorresponding to an RoHC packet excluding a CID from a header isindicated by R′k (k is 1, 2, . . . , or n).

The payload of the link layer packet may include R′k (k is 1, 2, . . . ,or n). A common CID field may be additionally provided to a tail of anextended header of the link layer packet. The common CID field may be afield for transmission of the common CID. The common CID field may betransmitted as a portion of the extended header or as a portion of thepayload of the link layer packet. Depending on a system operation, thecommon CID field may be appropriately rearranged at a portion forverification of a position.

The common CID field may have a size varying according to aconfiguration of the RoHC packet.

When the configuration of the RoHC packet corresponds to a small CIDconfiguration, the RoHC packet may have a CID size of 4 bits. Whenrearrangement is performed by extracting a CID from the RoHC packet, theentire add-CID octet may be processed. That is, the common CID field mayhave a length of 1 byte. Alternatively, after extracting a 1-byteadd-CID octet from the RoHC packet, only a 4-bit CID may be assigned tothe common CID field, and the remaining 4-bit CID may be reserved forlater use.

When the configuration of the RoHC packet corresponds to a large CIDconfiguration, the RoHC packet may have a CID size of 1 byte or 2 bytes.The CID size is determined in an RoHC initialization process. Dependingon the CID size, the common CID field may have a length of 1 byte or 2bytes.

In this case, the entire length LT of the link layer packet may becalculated as below.

$\begin{matrix}{L_{T} = {1 + L_{LP} + L_{CID} + {\sum\limits_{k = 1}^{n}\;{\left( {L_{k} - L_{CID}} \right)\mspace{14mu}\lbrack{bytes}\rbrack}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 22} \right\rbrack\end{matrix}$

Here, LCID may denote a length of the common CID field. As described inthe foregoing, LCID may be determined based on a CID configuration ofthe RoHC packet.

Similarly, when n is greater than or equal to 9 (the count field has avalue 11113), the entire length LT of the link layer packet may becalculated as below.

$\begin{matrix}{L_{T} = {1 + L_{LP} + L_{ELP} + L_{CID} + {\sum\limits_{k = 1}^{n}\;{\left( {L_{k} - L_{CID}} \right)\mspace{14mu}\lbrack{bytes}\rbrack}}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 23} \right\rbrack\end{matrix}$

Here, LCID may denote a length of the common CID field.

FIG. 88 illustrates a protocol stack for a hybrid-based next generationbroadcast system according to another embodiment of the presentinvention.

In a hybrid-based broadcast system of a TS and an IP stream, a linklayer may be used to transmit data having a TS or IP stream type. Whenvarious types of data are to be transmitted through a physical layer,the link layer may convert the data into a format supported by thephysical layer and deliver the converted data to the physical layer. Inthis way, the various types of data may be transmitted through the samephysical layer. Here, the physical layer may correspond to a step oftransmitting data using an MIMO/MISO scheme or the like by interleaving,multiplexing, and/or modulating the data.

The link layer needs to be designed such that an influence on anoperation of the link layer is minimized even when a configuration ofthe physical layer is changed. In other words, the operation of the linklayer needs to be configured such that the operation may be compatiblewith various physical layers.

The present invention proposes a link layer capable of independentlyoperating irrespective of types of an upper layer and a lower layer. Inthis way, it is possible to support various upper layers and lowerlayers. Here, the upper layer may refer to a layer of a data stream suchas a TS stream, an IP stream, or the like. Here, the lower layer mayrefer to the physical layer. In addition, the present invention proposesa link layer having a correctable structure in which a functionsupportable by the link layer may be extended/added/deleted. Moreover,the present invention proposes a scheme of including an overheadreduction function in the link layer such that radio resources may beefficiently used.

In this figure, protocols and layers such as IP, UDP, TCP, ALC/LCT,RCP/RTCP, HTTP, FLUTE, and the like are as described above.

In this figure, a link layer t88010 may be another example of theabove-described data link (encapsulation) part. The present inventionproposes a configuration and/or an operation of the link layer t88010.The link layer t88010 proposed by the present invention may processsignaling necessary for operations of the link layer and/or the physicallayer. In addition, the link layer t88010 proposed by the presentinvention may encapsulate TS and IP packets and the like, and performoverhead reduction in this process.

The link layer t88010 proposed by the present invention may be referredto by several terms such as data link layer, encapsulation layer, layer2, and the like. According to a given embodiment, a new term may beapplied to the link layer and used.

FIG. 89 illustrates an operation in a normal mode corresponding to oneof operation modes of a link layer according to an embodiment of thepresent invention.

The link layer proposed by the present invention may have variousoperation modes for compatibility between an upper layer and a lowerlayer. The present invention proposes a normal mode and a transparentmode of the link layer. Both the operation modes may coexist in the linklayer, and an operation mode to be used may be designated usingsignaling or a system parameter. According to a given embodiment, one ofthe two operation modes may be implemented. Different modes may beapplied according to an IP layer, a TS layer, and the like input to thelink layer. In addition, different modes may be applied for each streamof the IP layer and for each stream of the TS layer.

According to a given embodiment, a new operation mode may be added tothe link layer. The new operation mode may be added based onconfigurations of the upper layer and the lower layer. The new operationmode may include different interfaces based on the configurations of theupper layer and the lower layer. Whether to use the new operation modemay be designated using signaling or a system parameter.

In the normal mode, data may be processed through all functionssupported by the link layer, and then delivered to a physical layer.

First, each packet may be delivered to the link layer from an IP layer,an MPEG-2 TS layer, or another particular layer t89010. In other words,an IP packet may be delivered to the link layer from an IP layer.Similarly, an MPEG-2 TS packet may be delivered to the link layer fromthe MPEG-2 TS layer, and a particular packet may be delivered to thelink layer from a particular protocol layer.

Each of the delivered packets may go through or not go through anoverhead reduction process t89020, and then go through an encapsulationprocess t89030.

First, the IP packet may go through or not go through the overheadreduction process t89020, and then go through the encapsulation processt89030. Whether the overhead reduction process t89020 is performed maybe designated by signaling or a system parameter. According to a givenembodiment, the overhead reduction process t89020 may be performed ornot performed for each IP stream. An encapsulated IP packet may bedelivered to the physical layer.

Second, the MPEG-2 TS packet may go through the overhead reductionprocess t89020, and go through the encapsulation process t89030. TheMPEG-2 TS packet may not be subjected to the overhead reduction processt89020 according to a given embodiment. However, in general, a TS packethas sync bytes (0x47) and the like at the front and thus it may beefficient to eliminate such fixed overhead. The encapsulated TS packetmay be delivered to the physical layer.

Third, a packet other than the IP or TS packet may or may not go throughthe overhead reduction process t89020, and then go through theencapsulation process t89030. Whether or not the overhead reductionprocess t89020 is performed may be determined according tocharacteristics of the corresponding packet. Whether the overheadreduction process t89020 is performed may be designated by signaling ora system parameter. The encapsulated packet may be delivered to thephysical layer.

In the overhead reduction process t89020, a size of an input packet maybe reduced through an appropriate scheme. In the overhead reductionprocess t89020, particular information may be extracted from the inputpacket or generated. The particular information is information relatedto signaling, and may be transmitted through a signaling region. Thesignaling information enables a receiver to restore an original packetby restoring changes due to the overhead reduction process t89020. Thesignaling information may be delivered to a link layer signaling processt89050.

The link layer signaling process t89050 may transmit and manage thesignaling information extracted/generated in the overhead reductionprocess t89020. The physical layer may have physically/logically dividedtransmission paths for signaling, and the link layer signaling processt89050 may deliver the signaling information to the physical layeraccording to the divided transmission paths. Here, the above-describedFIC signaling process t89060, EAS signaling process t89070, or the likemay be included in the divided transmission paths. Signaling informationnot transmitted through the divided transmission paths may be deliveredto the physical layer through the encapsulation process t89030.

Signaling information managed by the link layer signaling process t89050may include signaling information delivered from the upper layer,signaling information generated in the link layer, a system parameter,and the like. Specifically, the signaling information may includesignaling information delivered from the upper layer to be subsequentlydelivered to an upper layer of the receiver, signaling informationgenerated in the link layer to be used for an operation of a link layerof the receiver, signaling information generated in the upper layer orthe link layer to be used for rapid detection in a physical layer of thereceiver, and the like.

Data going through the encapsulation process t89030 and delivered to thephysical layer may be transmitted through a data pipe (DP) t89040. Here,the DP may be a physical layer pipe (PLP). Signaling informationdelivered through the above-described divided transmission paths may bedelivered through respective transmission paths. For example, an FICsignal may be transmitted through an FIC t89080 designated in a physicalframe. In addition, an EAS signal may be transmitted through an EACt89090 designated in a physical frame. Information about presence of adedicated channel such as the FIC, the EAC, or the like may betransmitted to a preamble area of the physical layer through signaling,or signaled by scrambling a preamble using a particular scramblingsequence. According to a given embodiment, FIC signaling/EAS signalinginformation may be transmitted through a general DP area, PLS area, orpreamble rather than a designated dedicated channel.

The receiver may receive data and signaling information through thephysical layer. The receiver may restore the received data and signalinginformation into a form processable in the upper layer, and deliver therestored data and signaling information to the upper layer. This processmay be performed in the link layer of the receiver. The receiver mayverify whether a received packet is related to the signaling informationor the data by reading a header of the packet and the like. In addition,when overhead reduction is performed at a transmitter, the receiver mayrestore a packet, overhead of which has been reduced through theoverhead reduction process, to an original packet. In this process, thereceived signaling information may be used.

FIG. 90 illustrates an operation in a transparent mode corresponding toone of operation modes of a link layer according to an embodiment of thepresent invention.

In the transparent mode, data may not be subjected to functionssupported by the link layer or may be subjected to some of thefunctions, and then delivered to a physical layer. In other words, inthe transparent mode, a packet delivered to an upper layer may bedelivered to a physical layer without going through a separate overheadreduction and/or encapsulation process. Other packets may go through theoverhead reduction and/or encapsulation process as necessary. Thetransparent mode may be referred to as a bypass mode, and another termmay be applied to the transparent mode.

According to a given embodiment, some packets may be processed in thenormal mode and some packets may be processed in the transparent modebased on characteristics of the packets and a system operation.

A packet to which the transparent mode may be applied may be a packethaving a type well known to a system. When the packet may be processedin the physical layer, the transparent mode may be used. For example, awell-known TS or IP packet may go through separate overhead reductionand input formatting processes in the physical layer and thus thetransparent mode may be used in a link layer step. When the transparentmode is applied and a packet is processed through input formatting andthe like in the physical layer, an operation such as the above-describedTS header compression may be performed in the physical layer. On theother hand, when the normal mode is applied, a processed link layerpacket may be treated as a GS packet and processed in the physicallayer.

In the transparent mode, a link layer signaling module may be includedwhen signal transmission needs to be supported. As described above, thelink layer signaling module may transmit and manage signalinginformation. The signaling information may be encapsulated andtransmitted through a DP, and FIC signaling information and EASsignaling information having divided transmission paths may betransmitted through an FIC and an EAC, respectively.

In the transparent mode, whether information corresponds to signalinginformation may be displayed using a fixed IP address and port number.In this case, the signaling information may be filtered to configure alink layer packet, and then transmitted through the physical layer.

FIG. 91 illustrates a configuration of a link layer at a transmitteraccording to an embodiment of the present invention (normal mode).

The present embodiment is an embodiment presuming that an IP packet isprocessed. The link layer at the transmitter may largely include a linklayer signaling part for processing signaling information, an overheadreduction part, and/or an encapsulation part from a functionalperspective. The link layer at the transmitter may further include ascheduler t91020 for a control of the entire operation of the link layerand scheduling, input and output parts of the link layer, and/or thelike.

First, upper layer signaling information and/or system parameter t91010may be delivered to the link layer. In addition, an IP stream includingIP packets may be delivered to the link layer from an IP layer t91110.

As described above, the scheduler t91020 may determine and controloperations of several modules included in the link layer. The deliveredsignaling information and/or system parameter t91010 may be filtered orused by the scheduler t91020. Information corresponding to a part of thedelivered signaling information and/or system parameter t91010 andnecessary for a receiver may be delivered to the link layer signalingpart. In addition, information corresponding to a part of the signalinginformation and necessary for an operation of the link layer may bedelivered to an overhead reduction control block t91120 or anencapsulation control block t91180.

The link layer signaling part may collect information to be transmittedas signaling in the physical layer, and transform/configure theinformation in a form suitable for transmission. The link layersignaling part may include a signaling manager t91030, a signalingformatter t91040, and/or a buffer for channels t91050.

The signaling manager t91030 may receive signaling information deliveredfrom the scheduler t91020, signaling delivered from the overheadreduction part, and/or context information. The signaling manager t91030may determine paths for transmission of the signaling information withrespect to delivered data. The signaling information may be deliveredthrough the paths determined by the signaling manager t91030. Asdescribed in the foregoing, signaling information to be transmittedthrough divided channels such as an FIC, an EAS, and the like may bedelivered to the signaling formatter t91040, and other signalinginformation may be delivered to an encapsulation buffer t91070.

The signaling formatter t91040 may format associated signalinginformation in forms suitable for respective divided channels so thatthe signaling information may be transmitted through separately dividedchannels. As described in the foregoing, the physical layer may includephysically/logically divided separate channels. The divided channels maybe used to transmit FIC signaling information or EAS-relatedinformation. The FIC or EAS-related information may be divided by thesignaling manager t91030 and input to the signaling formatter t91040.The signaling formatter t91040 may format information such that theinformation is suitable for respective separate channels. Besides theFIC and the EAS, when the physical layer is designed to transmitparticular signaling information through separately divided channels, asignaling formatter for the particular signaling information may beadded. Through this scheme, the link layer may be compatible withvarious physical layers.

The buffer for channels t91050 may deliver signaling informationdelivered from the signaling formatter t91040 to designated dedicatedchannels t91060. The number and content of the dedicated channels t91060may vary depending on an embodiment.

As described in the foregoing, the signaling manager t91030 may deliversignaling information which is not delivered to a dedicated channel tothe encapsulation buffer t91070. The encapsulation buffer t91070 mayfunction as a buffer that receives the signaling information notdelivered to the dedicated channel.

An encapsulation for signaling information t91080 may encapsulate thesignaling information not delivered to the dedicated channel. Atransmission buffer t91090 may function as a buffer that delivers theencapsulated signaling information to a DP for signaling informationt91100. Here, the DP for signaling information t91100 may refer to theabove-described PLS area.

The overhead reduction part may allow efficient transmission byeliminating overhead of packets delivered to the link layer. It ispossible to configure overhead reduction parts, the number of which isthe same as the number of IP streams input to the link layer.

An overhead reduction buffer t91130 may receive an IP packet deliveredfrom an upper layer. The delivered IP packet may be input to theoverhead reduction part through the overhead reduction buffer t91130.

An overhead reduction control block t91120 may determine whether toperform overhead reduction on a packet stream input to the overheadreduction buffer t91130. The overhead reduction control block t91120 maydetermine whether to perform overhead reduction for each packet stream.When overhead reduction is performed on the packet stream, packets maybe delivered to an RoHC compressor t91140 and overhead reduction may beperformed. When overhead reduction is not performed on the packetstream, packets may be delivered to the encapsulation part andencapsulation may be performed without overhead reduction. Whether toperform overhead reduction on packets may be determined by signalinginformation t91010 delivered to the link layer. The signalinginformation t91010 may be delivered to the encapsulation control blockt91180 by the scheduler t91020.

The RoHC compressor t91140 may perform overhead reduction on a packetstream. The RoHC compressor t91140 may compress headers of packets.Various schemes may be used for overhead reduction. Overhead reductionmay be performed by schemes proposed in the present invention. Thepresent embodiment presumes an IP stream and thus the compressor isexpressed as the RoHC compressor. However, the term may be changedaccording to a given embodiment. In addition, an operation is notrestricted to compression of an IP stream, and overhead reduction may beperformed on all types of packets by the RoHC compressor t91140.

A packet stream configuration block t91150 may divide IP packets havingcompressed headers into information to be transmitted to a signalingregion and information to be transmitted to a packet stream. Theinformation to be transmitted to the packet stream may refer toinformation to be transmitted to a DP area. The information to betransmitted to the signaling region may be delivered to a signalingand/or context control block t91160. The information to be transmittedto the packet stream may be transmitted to the encapsulation part.

The signaling and/or context control block t91160 may collect signalingand/or context information and deliver the collected information to thesignaling manager t91030. In this way, the signaling and/or contextinformation may be transmitted to the signaling region.

The encapsulation part may encapsulate packets in suitable forms suchthat the packets may be delivered to the physical layer. The number ofconfigured encapsulation parts may be the same as the number of IPstreams.

An encapsulation buffer t91170 may receive a packet stream forencapsulation. Packets subjected to overhead reduction may be receivedwhen overhead reduction is performed, and an input IP packet may bereceived without change when overhead reduction is not performed.

An encapsulation control block t91180 may determine whether to performencapsulation on an input packet stream. When encapsulation isperformed, the packet stream may be delivered tosegmentation/concatenation t91190. When encapsulation is not performed,the packet stream may be delivered to a transmission buffer t91230.Whether to perform encapsulation of packets may be determined based onthe signaling information t91010 delivered to the link layer. Thesignaling information t91010 may be delivered to the encapsulationcontrol block t91180 by the scheduler t91020.

In the segmentation/concatenation t91190, the above-descriedsegmentation or concatenation operation may be performed on packets. Inother words, when an input IP packet is longer than a link layer packetcorresponding to an output of the link layer, one IP packet may bedivided into several segments to configure a plurality of link layerpacket payloads. In addition, when the input IP packet is shorter thanthe link layer packet corresponding to the output of the link layer,several IP packets may be combined to configure one link layer packetpayload.

A packet configuration table t91200 may have information about aconfiguration of segmented and/or concatenated link layer packets. Atransmitter and a receiver may have the same information of the packetconfiguration table t91200. The transmitter and the receiver may referto the information of the packet configuration table t91200. An indexvalue of the information of the packet configuration table t91200 may beincluded in headers of the link layer packets.

A link layer header information block t91210 may collect headerinformation generated in an encapsulation process. In addition, the linklayer header information block t91210 may collect information includedin the packet configuration table t91200. The link layer headerinformation block t91210 may configure header information according to aheader configuration of a link layer packet.

A header attachment block t91220 may add headers to payloads of thesegmented and/or concatenated link layer packets. The transmissionbuffer t91230 may function as a buffer for delivering a link layerpacket to a DP t91240 of the physical layer.

Each block or module and parts may be configured as one module/protocolor a plurality of modules/protocols in the link layer.

FIG. 92 illustrates a configuration of a link layer at a receiveraccording to an embodiment of the present invention (normal mode).

The present embodiment is an embodiment presuming that an IP packet isprocessed. The link layer at the receiver may largely include a linklayer signaling part for processing signaling information, an overheadprocessing part, and/or a decapsulation part from a functionalperspective. The link layer at the receiver may further include ascheduler for a control of the entire operation of the link layer andscheduling, input and output parts of the link layer, and/or the like.

First, information received through a physical layer may be delivered tothe link layer. The link layer may process the information to restorethe information to an original state in which the information is not yetprocessed by a transmitter, and deliver the information to an upperlayer. In the present embodiment, the upper layer may be an IP layer.

Information delivered through dedicated channels t92030 separated fromthe physical layer may be delivered to the link layer signaling part.The link layer signaling part may distinguish signaling informationreceived from the physical layer, and deliver the distinguishedsignaling information to each part of the link layer.

A buffer for channels t92040 may function as a buffer that receivessignaling information transmitted through the dedicated channels. Asdescribed above, when physically/logically divided separate channels arepresent in the physical layer, it is possible to receive signalinginformation transmitted through the channels. When the informationreceived from the separate channels is in a divided state, the dividedinformation may be stored until the information is in a complete form.

A signaling decoder/parser t92050 may check a format of signalinginformation received through a dedicated channel, and extractinformation to be used in the link layer. When the signaling informationreceived through the dedicated channel is encoded, decoding may beperformed. In addition, according to a given embodiment, it is possibleto check integrity of the signaling information.

A signaling manager t92060 may integrate signaling information receivedthrough several paths. Signaling information received through a DP forsignaling t92070 to be described below may be integrated by thesignaling manager t92060. The signaling manager t92060 may deliversignaling information necessary for each part in the link layer. Forexample, context information for recovery of a packet and the like maybe delivered to the overhead processing part. In addition, signalinginformation for control may be delivered to a scheduler t92020.

General signaling information not received through a separate dedicatedchannel may be received through the DP for signaling t92070. Here, theDP for signaling may refer to a PLS or the like. A reception buffert92080 may function as a buffer for receiving the signaling informationreceived from the DP for signaling t92070. The received signalinginformation may be decapsulated in a decapsulation for signalinginformation block t92090. The decapsulated signaling information may bedelivered to the signaling manager t92060 through a decapsulation buffert92100. As described in the foregoing, the signaling manager t92060 maycollect signaling information and deliver the collected signalinginformation to a desired part in the link layer.

The scheduler t92020 may determine and control operations of severalmodules included in the link layer. The scheduler t92020 may controleach part of the link layer using receiver information t92010 and/orinformation delivered from the signaling manager t92060. In addition,the scheduler t92020 may determine an operation mode and the like ofeach part. Here, the receiver information t92010 may refer toinformation previously stored by the receiver. The scheduler t92020 mayuse information changed by a user such as a channel change and the likefor control.

The decapsulation part may filter a packet received from a DP t92110 ofthe physical layer, and separate the packet based on a type of thepacket. The number of configured decapsulation parts may be the same asthe number of DPs that may be simultaneously decoded in the physicallayer.

A decapsulation buffer t92120 may function as a buffer that receives apacket stream from the physical layer to perform decapsulation. Adecapsulation control block t92130 may determine whether to decapsulatethe received packet stream. When decapsulation is performed, the packetstream may be delivered to a link layer header parser t92140. Whendecapsulation is not performed, the packet stream may be delivered to anoutput buffer t92220. The signaling information delivered from thescheduler t92020 may be used to determine whether to performdecapsulation.

The link layer header parser t92140 may identify a header of a receivedlink layer packet. When the header is identified, it is possible toidentify a configuration of an IP packet included in a payload of thelink layer packet. For example, the IP packet may be segmented orconcatenated.

A packet configuration table t92150 may include payload information oflink layer packets configured through segmentation and/or concatenation.The transmitter and the receiver may have the same information asinformation of the packet configuration table t92150. The transmitterand the receiver may refer to the information of the packetconfiguration table t92150. A value necessary for reassembly may befound based on index information included in the link layer packets.

A reassembly block t92160 may configure payloads of the link layerpackets configured through segmentation and/or concatenation as packetsof an original IP stream. The reassembly block t92160 may reconfigureone IP packet by collecting segments, or reconfigure a plurality of IPpacket streams by separating concatenated packets. The reassembled IPpackets may be delivered to the overhead processing part.

The overhead processing part may perform a reverse process of overheadreduction performed by the transmitter. In the reverse process, anoperation of returning packets experiencing overhead reduction tooriginal packets is performed. This operation may be referred to asoverhead processing. The number of configured overhead processing partsmay be the same as the number of DPs that may be simultaneously decodedin the physical layer.

A packet recovery buffer t92170 may function as a buffer that receivesan RoHC packet or an IP packet decapsulated for overhead processing.

An overhead control block t92180 may determine whether to perform packetrecovery and/or decompression of decapsulated packets. When the packetrecovery and/or decompression are performed, the packets may bedelivered to a packet stream recovery t92190. When the packet recoveryand/or decompression are not performed, the packets may be delivered tothe output buffer t92220. Whether to perform the packet recovery and/ordecompression may be determined based on the signaling informationdelivered by the scheduler t92020.

The packet stream recovery t92190 may perform an operation ofintegrating a packet stream separated from the transmitter and contextinformation of the packet stream. The operation may correspond to aprocess of restoring the packet stream such that the packet stream maybe processed by an RoHC decompressor t92210. In this process, signalinginformation and/or context information may be delivered from a signalingand/or context control block t92200. The signaling and/or contextcontrol block t92200 may distinguish signaling information deliveredfrom the transmitter and deliver the signaling information to the packetstream recovery t92190 such that the signaling information may be mappedto a stream suitable for a context ID.

The RoHC decompressor t92210 may recover headers of packets of a packetstream. When the headers are recovered, the packets of the packet streammay be restored to original IP packets. In other words, the RoHCdecompressor t92210 may perform overhead processing.

The output buffer t92220 may function as a buffer before delivering anoutput stream to an IP layer t92230.

The link layer of the transmitter and the receiver proposed in thepresent invention may include the blocks or modules described above. Inthis way, the link layer may independently operate irrespective of theupper layer and the lower layer, and efficiently perform overheadreduction. In addition, a function which is supportable depending on theupper and lower layers may be easily extended/added/deleted.

FIG. 93 illustrates a method of transmitting broadcast signals accordingto an embodiment of the present invention.

The method includes generating plural input streams, link layerprocessing the input packets, physical layer processing the link layerpackets and/or transmitting the generated broadcast signals.

In step of generating plural input streams, the input streams includingplural input packets can be generated in upper layer. Upper layer can beeither TS layer, IP layer or other types of packet layer. Therefore, theinput packets can be either TS packets, IP packets or other packets.Input stream includes consecutive input packets.

In step of link layer processing the input packets, the input packetscan be processed by the link layer described above. The link layer canbe the one suggested by the present invention. By processing inputpackets in the link layer, the link layer packets can be generated. Byprocessing any types of input packets into the link layer packet, anyinput streams can be processed by the physical layer.

In step of physical layer processing the link layer packets, the linklayer packets can be processed in physical layer. The link layer packetscan go through interleaving, frame mapping, and/or modulating and so on.With this process, the broadcast signals can be generated.

In step of transmitting the generated broadcast signals, the broadcastsignals can be transmitted by either SISO, MISO, or MIMO. Thetransmitting can be included in physical layer.

In a method of transmitting broadcast signals according to otherembodiment of the present invention, the link layer processing includeslink layer processing one of the plural input streams based ontransparent mode. As described above, there can be two modes for linklayer processing, normal and transparent. In link layer processing, someof input streams can be processed in transparent mode, while the othersare processed in normal mode. In transparent mode, the link layerdelivers the one of the plural input streams to the physical layerwithout encapsulating. Signaling information supposed to be transmittedin a dedicated channel, can be delivered to that channel in the physicallayer. Some types of packets can go through encapsulating, even in thetransparent mode, as described above.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the link layer processing in normalmode includes encapsulating and/or delivering. The link layer processingone of the plural input streams includes encapsulating the input packetsin the one of the plural input streams to generate the link layerpackets. The generated link layer packets can be delivered to thephysical layer.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the link layer processing in normalmode includes overhead reduction processing the input packets beforeencapsulating. The overhead reduction process can be conducted after theencapsulating in other embodiments. The overhead reduction process caninclude compress headers of the input packets. Other method of overheadreduction can be used in link layer.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the link layer processing in normalmode includes extracting a first signaling information and/ordelivering. The first signaling information can be extracted fromoverhead reduction processed input packets. The first signalinginformation is a signaling information to be transmitted in a dedicatedtransmission channel. The above described EAS, FIC information cancorrespond to the first signaling information. The first signalinginformation can be delivered to the dedicated channel for the firstsignaling information, in the physical layer.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the link layer processing in normalmode includes extracting a second signaling information, encapsulatingthe second signaling information and/or delivering. The second signalinginformation is for signaling data in the input packets. The secondsignaling information can be encapsulated as in the encapsulation ofinput packets. The second signaling information can be encapsulated intothe link layer packets. The link layer packet generated by using thesecond signaling information can be delivered to the physical layer. Thesecond signaling information can be transmitted in DP or PLS, asdescribed above.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the link layer packet includes alink layer payload generated by using a segment of one of the inputpackets, or by using concatenated input packets. As described above, thelink layer payload can be encapsulated by segmentation or concatenation.Various methods of segmentation and concatenation have been described.Segmentation and concatenation methods for each types of input packetscan be used in encapsulation. Whether the segmentation or theconcatenation is used can be decided based on signaling information.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the physical layer processingincludes physical layer processing plural Plops (Physical Layer Pipes).The PLP may correspond to the DP. The PLP can include data of the linklayer packets, and be processed in physical layer. The link layer can beprocessed in physical layer as in forms of Plops.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the physical layer processingincludes physical layer processing the first signaling information. Thefirst signaling information can be processed into the dedicatedtransmission channel, to generate the broadcast signals.

In a method of transmitting broadcast signals according to anotherembodiment of the present invention, the input packets are one of TS(Transport Stream) packet, IP (Internet Protocol) packet or GS (GenericStream) packet. The input packets can be some types of packets otherthan TS, IP or GS packets.

The above-described steps can be omitted or replaced by steps executingsimilar or identical functions according to design.

A module or a unit is a processor executing a sequence of instructionsstored in a memory (or storage unit). The steps in above describedembodiments can be operated in hardware/processors. The first module,second module, third module and/or fourth module can be operated ashardware/processors. In addition, a method of transmitting broadcastsignals according to an embodiment of the present invention may beimplemented as code that may be written on a processor readablerecording medium and thus, read by a processor provided in theapparatus.

Although the description of the present invention is explained withreference to each of the accompanying drawings for clarity, it ispossible to design new embodiment(s) by merging the embodiments shown inthe accompanying drawings with each other. And, if a recording mediumreadable by a computer, in which programs for executing the embodimentsmentioned in the foregoing description are recorded, is designed innecessity of those skilled in the art, it may belong to the scope of theappended claims and their equivalents.

An apparatus and method according to the present invention may benon-limited by the configurations and methods of the embodimentsmentioned in the foregoing description. And, the embodiments mentionedin the foregoing description can be configured in a manner of beingselectively combined with one another entirely or in part to enablevarious modifications.

In addition, a method according to the present invention can beimplemented with processor-readable codes in a processor-readablerecording medium provided to a network device. The processor-readablemedium may include all kinds of recording devices capable of storingdata readable by a processor. The processor-readable medium may includeone of ROM, RAM, CD-ROM, magnetic tapes, floppy discs, optical datastorage devices, and the like for example and also include such acarrier-wave type implementation as a transmission via Internet.Furthermore, as the processor-readable recording medium is distributedto a computer system connected via network, processor-readable codes canbe saved and executed according to a distributive system.

It will be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

Various embodiments have been described in the best mode for carryingout the invention.

The present invention is available in a series of broadcast signalprovision fields.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of transmitting broadcast signals, themethod comprising: generating input packets; link processing the inputpackets to generate link layer packets, wherein the link processingincludes: generating a payload of a link layer packet by encapsulating asegment of one input packet or concatenated input packets, generating aheader of the link layer packet including a first field for identifyingwhether the payload includes either the segment or the concatenatedinput packets, and inserting the header in front of the payload;physical processing the link layer packets into the broadcast signals;and transmitting the broadcast signals, wherein the header includes asecond field for identifying a number of the concatenated input packetsand third fields that are inserted to the header in the same order asthe concatenated input packets present in the payload in response to thefirst field representing that the payload includes the concatenatedinput packets, wherein a value of the second field is set to the numberof the concatenated input packets−2, wherein the third fields representa length of each of the concatenated input packets, wherein a number ofthe third fields is determined based on the number of the concatenatedinput packets in the payload, and wherein stuffing bits are added afterthe third fields in response to the determination that the number of thethird fields is odd.
 2. The method of claim 1, wherein the headerfurther includes a fourth field for identifying a type of the inputpackets included in the payload.
 3. An apparatus for transmittingbroadcast signals, the apparatus comprising: a processor to generateinput packets, wherein the processor is further to link process theinput packets to generate link layer packets, wherein, to link processthe input packets, the processor is further to: generate a payload of alink layer packet by encapsulating a segment of one input packet orconcatenated input packets, generate a header of the link layer packetincluding a first field for identifying whether the payload includeseither the segment or the concatenated input packets, and insert theheader in front of the payload, wherein the processor is further tophysical process the link layer packets into the broadcast signals; anda transmitter to transmit the broadcast signals, wherein the headerfurther includes a second field for identifying a number of theconcatenated input packets and third fields that are inserted to theheader in the same order as the concatenated input packets present inthe payload in response to the first field representing that the payloadincludes the concatenated input packets, wherein a value of the secondfield is set to the number of the concatenated input packets−2, whereinthe third fields represents a length of each of the concatenated inputpackets, wherein a number of the third fields is determined based on thenumber of the concatenated input packets in the payload, and whereinstuffing bits are added after the third fields in response to thedetermination the number of the third fields is odd.
 4. The apparatus ofclaim 3, wherein the header further includes a fourth field foridentifying a type of the input packets included in the payload.
 5. Amethod of receiving broadcast signals, the method comprising: receivingthe broadcast signals; physical processing the broadcast signals intolink layer packets; and link processing the link layer packets torestore input packets, wherein the link processing includes: extractinga header from a link layer packet, obtaining a first field foridentifying whether a payload of the link layer packet includes asegment of one input packet or concatenated input packets from theheader, obtaining a second field for identifying a number of theconcatenated input packets and third fields for identifying a length ofeach of the concatenated input packets from the header in response tothe first field representing that the payload includes the concatenatedinput packets, wherein a value of the second field is set to the numberof the concatenated input packets−2, and wherein a number of the thirdfields is determined based on the number of the concatenated inputpackets in the payload, and restoring the input packets, bydecapsulating the payload of the link layer packet and by dividing theconcatenated input packets in the same order as the third fields basedon the second field and the third fields.
 6. The method of claim 5,further comprising: disregarding stuffing bits after the third fields inresponse to the determination that the number of the third fields isodd.
 7. The method of claim 5, wherein the header further includes afourth field for identifying a type of the input packets included in thepayload.
 8. An apparatus for receiving broadcast signals, the apparatuscomprising: a tuner to receive the broadcast signals; and a processor tophysical process the broadcast signals into link layer packets, whereinthe processor is further to link process the link layer packets torestore input packets, wherein, to link process the link layer packets,the processor is further to: extract a header from a link layer packet,obtain a first field for identifying whether a payload of the link layerpacket includes a segment of one input packet or concatenated inputpackets from the header, obtain a second field for identifying a numberof the concatenated input packets and third fields for identifying alength of each of the concatenated input packets from the header inresponse to the first field representing that the payload includes theconcatenated input packets, wherein a value of the second field is setto the number of the concatenated input packets−2 and wherein a numberof the third fields is determined based on the number of theconcatenated input packets in the payload, and restore the inputpackets, by decapsulating the payload of the link layer packet and bydividing the concatenated input packets in the same order as the thirdfields based on the second field and the third fields.
 9. The apparatusof claim 8, wherein, to link process the link layer packets, theprocessor is further to: disregard stuffing bits after the third fieldsin response to the determination that the number of the third fields isodd.
 10. The apparatus of claim 8, wherein the header further includes afourth field for identifying a type of the input packets included in thepayload.